From 003eb6e48d85ad77ebd94ec2858f033d0c36beac Mon Sep 17 00:00:00 2001
From: Scott Lewis <scottslewis@gmail.com>
Date: Wed, 28 Jan 2026 15:43:23 -0800
Subject: [PATCH 1/4] Rebasing on main after #742 merged. Moves mcp-json API
 back into mcp-core so that mcp-json API is no longer needed and mcp-core has
 fewer dependencies.

---
 mcp-bom/pom.xml                               |  7 --
 mcp-core/pom.xml                              | 18 ++--
 .../client/McpClient.java                     | 12 ++-
 .../HttpClientSseClientTransport.java         |  3 +-
 .../HttpClientStreamableHttpTransport.java    |  8 +-
 .../json/McpJsonDefaults.java                 | 50 +++++++++++
 .../json/McpJsonMapper.java                   | 90 +++++++++++++++++++
 .../json/McpJsonMapperSupplier.java           | 14 +++
 .../io/modelcontextprotocol/json/TypeRef.java | 44 +++++++++
 .../DefaultMcpJsonMapperSupplier.java         | 40 +++++++++
 ...DefaultMcpJsonSchemaValidatorSupplier.java | 42 +++++++++
 .../json/schema/JsonSchemaValidator.java      | 44 +++++++++
 .../schema/JsonSchemaValidatorSupplier.java   | 19 ++++
 .../server/McpServer.java                     | 40 +++++----
 ...HttpServletSseServerTransportProvider.java |  5 +-
 .../HttpServletStatelessServerTransport.java  |  6 +-
 ...vletStreamableServerTransportProvider.java |  5 +-
 .../util/McpServiceLoader.java                | 50 +++++++++++
 ...elcontextprotocol.json.McpJsonDefaults.xml |  9 ++
 .../MockMcpClientTransport.java               |  4 +-
 .../MockMcpServerTransport.java               |  4 +-
 .../CompleteCompletionSerializationTest.java  |  3 +-
 .../util/McpJsonMapperUtils.java              |  3 +-
 mcp-json-jackson2/pom.xml                     | 47 ++++++++--
 ....jackson2.JacksonMcpJsonMapperSupplier.xml |  7 ++
 ...on2.JacksonJsonSchemaValidatorSupplier.xml |  7 ++
 .../json/McpJsonMapperTest.java               |  2 +-
 .../json/schema/JsonSchemaValidatorTest.java  |  3 +-
 mcp-json-jackson3/pom.xml                     | 42 +++++++--
 ....jackson3.JacksonMcpJsonMapperSupplier.xml |  7 ++
 ...on3.JacksonJsonSchemaValidatorSupplier.xml |  7 ++
 .../json/McpJsonMapperTest.java               |  2 +-
 .../json/schema/JsonSchemaValidatorTest.java  |  3 +-
 .../WebClientStreamableHttpTransport.java     |  6 +-
 .../transport/WebFluxSseClientTransport.java  |  3 +-
 .../WebFluxSseServerTransportProvider.java    |  6 +-
 .../WebFluxStatelessServerTransport.java      |  6 +-
 ...FluxStreamableServerTransportProvider.java |  5 +-
 .../utils/McpJsonMapperUtils.java             |  3 +-
 .../WebMvcSseServerTransportProvider.java     |  6 +-
 .../WebMvcStatelessServerTransport.java       |  6 +-
 ...bMvcStreamableServerTransportProvider.java |  5 +-
 ...WebMvcSseServerTransportProviderTests.java |  3 +-
 .../MockMcpTransport.java                     |  4 +-
 .../util/McpJsonMapperUtils.java              |  3 +-
 pom.xml                                       |  1 -
 46 files changed, 605 insertions(+), 99 deletions(-)
 create mode 100644 mcp-core/src/main/java/io/modelcontextprotocol/json/McpJsonDefaults.java
 create mode 100644 mcp-core/src/main/java/io/modelcontextprotocol/json/McpJsonMapper.java
 create mode 100644 mcp-core/src/main/java/io/modelcontextprotocol/json/McpJsonMapperSupplier.java
 create mode 100644 mcp-core/src/main/java/io/modelcontextprotocol/json/TypeRef.java
 create mode 100644 mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonMapperSupplier.java
 create mode 100644 mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonSchemaValidatorSupplier.java
 create mode 100644 mcp-core/src/main/java/io/modelcontextprotocol/json/schema/JsonSchemaValidator.java
 create mode 100644 mcp-core/src/main/java/io/modelcontextprotocol/json/schema/JsonSchemaValidatorSupplier.java
 create mode 100644 mcp-core/src/main/java/io/modelcontextprotocol/util/McpServiceLoader.java
 create mode 100644 mcp-core/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.McpJsonDefaults.xml
 create mode 100644 mcp-json-jackson2/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.jackson2.JacksonMcpJsonMapperSupplier.xml
 create mode 100644 mcp-json-jackson2/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.schema.jackson2.JacksonJsonSchemaValidatorSupplier.xml
 create mode 100644 mcp-json-jackson3/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.jackson3.JacksonMcpJsonMapperSupplier.xml
 create mode 100644 mcp-json-jackson3/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.schema.jackson3.JacksonJsonSchemaValidatorSupplier.xml

diff --git a/mcp-bom/pom.xml b/mcp-bom/pom.xml
index 447c9e0bd..f3d76d819 100644
--- a/mcp-bom/pom.xml
+++ b/mcp-bom/pom.xml
@@ -40,13 +40,6 @@
                 <version>${project.version}</version>
             </dependency>
 
-            <!-- MCP JSON -->
-            <dependency>
-                <groupId>io.modelcontextprotocol.sdk</groupId>
-                <artifactId>mcp-json</artifactId>
-                <version>${project.version}</version>
-            </dependency>
-
             <!-- MCP JSON Jackson -->
             <dependency>
                 <groupId>io.modelcontextprotocol.sdk</groupId>
diff --git a/mcp-core/pom.xml b/mcp-core/pom.xml
index 0c8650f46..989764873 100644
--- a/mcp-core/pom.xml
+++ b/mcp-core/pom.xml
@@ -65,11 +65,6 @@
 	</build>
 
 	<dependencies>
-        <dependency>
-            <groupId>io.modelcontextprotocol.sdk</groupId>
-            <artifactId>mcp-json</artifactId>
-            <version>0.18.0-SNAPSHOT</version>
-        </dependency>
 
 		<dependency>
 			<groupId>org.slf4j</groupId>
@@ -97,14 +92,6 @@
 			<scope>provided</scope>
 		</dependency>
 
-		<!-- Test dependencies -->
-        <dependency>
-            <groupId>io.modelcontextprotocol.sdk</groupId>
-            <artifactId>mcp-json-jackson3</artifactId>
-            <version>0.18.0-SNAPSHOT</version>
-            <scope>test</scope>
-        </dependency>
-
 		<dependency>
 			<groupId>org.springframework</groupId>
 			<artifactId>spring-webmvc</artifactId>
@@ -112,6 +99,11 @@
 			<scope>test</scope>
 		</dependency>
 
+        <dependency>
+            <groupId>tools.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson3.version}</version>
+        </dependency>
 
 		<dependency>
 			<groupId>io.projectreactor.netty</groupId>
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/client/McpClient.java b/mcp-core/src/main/java/io/modelcontextprotocol/client/McpClient.java
index c9989f832..1210b9078 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/client/McpClient.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/client/McpClient.java
@@ -5,6 +5,7 @@
 package io.modelcontextprotocol.client;
 
 import io.modelcontextprotocol.common.McpTransportContext;
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.schema.JsonSchemaValidator;
 import io.modelcontextprotocol.spec.McpClientTransport;
 import io.modelcontextprotocol.spec.McpSchema;
@@ -491,9 +492,12 @@ public McpSyncClient build() {
 
 			McpClientFeatures.Async asyncFeatures = McpClientFeatures.Async.fromSync(syncFeatures);
 
-			return new McpSyncClient(new McpAsyncClient(transport, this.requestTimeout, this.initializationTimeout,
-					jsonSchemaValidator != null ? jsonSchemaValidator : JsonSchemaValidator.getDefault(),
-					asyncFeatures), this.contextProvider);
+			return new McpSyncClient(
+					new McpAsyncClient(transport, this.requestTimeout, this.initializationTimeout,
+							jsonSchemaValidator != null ? jsonSchemaValidator
+									: McpJsonDefaults.getDefaultJsonSchemaValidator(),
+							asyncFeatures),
+					this.contextProvider);
 		}
 
 	}
@@ -826,7 +830,7 @@ public AsyncSpec enableCallToolSchemaCaching(boolean enableCallToolSchemaCaching
 		 */
 		public McpAsyncClient build() {
 			var jsonSchemaValidator = (this.jsonSchemaValidator != null) ? this.jsonSchemaValidator
-					: JsonSchemaValidator.getDefault();
+					: McpJsonDefaults.getDefaultJsonSchemaValidator();
 			return new McpAsyncClient(this.transport, this.requestTimeout, this.initializationTimeout,
 					jsonSchemaValidator,
 					new McpClientFeatures.Async(this.clientInfo, this.capabilities, this.roots,
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/HttpClientSseClientTransport.java b/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/HttpClientSseClientTransport.java
index ae093316f..b9ed2711d 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/HttpClientSseClientTransport.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/HttpClientSseClientTransport.java
@@ -22,6 +22,7 @@
 import io.modelcontextprotocol.client.transport.customizer.McpAsyncHttpClientRequestCustomizer;
 import io.modelcontextprotocol.client.transport.customizer.McpSyncHttpClientRequestCustomizer;
 import io.modelcontextprotocol.common.McpTransportContext;
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 import io.modelcontextprotocol.json.TypeRef;
 import io.modelcontextprotocol.spec.HttpHeaders;
@@ -327,7 +328,7 @@ public Builder connectTimeout(Duration connectTimeout) {
 		public HttpClientSseClientTransport build() {
 			HttpClient httpClient = this.clientBuilder.connectTimeout(this.connectTimeout).build();
 			return new HttpClientSseClientTransport(httpClient, requestBuilder, baseUri, sseEndpoint,
-					jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper, httpRequestCustomizer);
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, httpRequestCustomizer);
 		}
 
 	}
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/HttpClientStreamableHttpTransport.java b/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/HttpClientStreamableHttpTransport.java
index 0a8dff363..20ad02691 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/HttpClientStreamableHttpTransport.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/HttpClientStreamableHttpTransport.java
@@ -25,6 +25,7 @@
 import io.modelcontextprotocol.client.transport.customizer.McpAsyncHttpClientRequestCustomizer;
 import io.modelcontextprotocol.client.transport.customizer.McpSyncHttpClientRequestCustomizer;
 import io.modelcontextprotocol.common.McpTransportContext;
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 import io.modelcontextprotocol.json.TypeRef;
 import io.modelcontextprotocol.spec.ClosedMcpTransportSession;
@@ -822,9 +823,10 @@ public Builder supportedProtocolVersions(List<String> supportedProtocolVersions)
 		 */
 		public HttpClientStreamableHttpTransport build() {
 			HttpClient httpClient = this.clientBuilder.connectTimeout(this.connectTimeout).build();
-			return new HttpClientStreamableHttpTransport(jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper,
-					httpClient, requestBuilder, baseUri, endpoint, resumableStreams, openConnectionOnStartup,
-					httpRequestCustomizer, supportedProtocolVersions);
+			return new HttpClientStreamableHttpTransport(
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, httpClient,
+					requestBuilder, baseUri, endpoint, resumableStreams, openConnectionOnStartup, httpRequestCustomizer,
+					supportedProtocolVersions);
 		}
 
 	}
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/json/McpJsonDefaults.java b/mcp-core/src/main/java/io/modelcontextprotocol/json/McpJsonDefaults.java
new file mode 100644
index 000000000..e0a5da370
--- /dev/null
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/json/McpJsonDefaults.java
@@ -0,0 +1,50 @@
+package io.modelcontextprotocol.json;
+
+import io.modelcontextprotocol.json.schema.JsonSchemaValidator;
+import io.modelcontextprotocol.json.schema.JsonSchemaValidatorSupplier;
+import io.modelcontextprotocol.util.McpServiceLoader;
+
+public class McpJsonDefaults {
+
+	protected static McpServiceLoader<McpJsonMapperSupplier, McpJsonMapper> mcpMapperServiceLoader;
+
+	protected static McpServiceLoader<JsonSchemaValidatorSupplier, JsonSchemaValidator> mcpValidatorServiceLoader;
+
+	public McpJsonDefaults() {
+		mcpMapperServiceLoader = new McpServiceLoader<McpJsonMapperSupplier, McpJsonMapper>(
+				McpJsonMapperSupplier.class);
+		mcpValidatorServiceLoader = new McpServiceLoader<JsonSchemaValidatorSupplier, JsonSchemaValidator>(
+				JsonSchemaValidatorSupplier.class);
+	}
+
+	void setMcpJsonMapperSupplier(McpJsonMapperSupplier supplier) {
+		mcpMapperServiceLoader.setSupplier(supplier);
+	}
+
+	void unsetMcpJsonMapperSupplier(McpJsonMapperSupplier supplier) {
+		mcpMapperServiceLoader.unsetSupplier(supplier);
+	}
+
+	public synchronized static McpJsonMapper getDefaultMcpJsonMapper() {
+		if (mcpMapperServiceLoader == null) {
+			new McpJsonDefaults();
+		}
+		return mcpMapperServiceLoader.getDefault();
+	}
+
+	void setJsonSchemaValidatorSupplier(JsonSchemaValidatorSupplier supplier) {
+		mcpValidatorServiceLoader.setSupplier(supplier);
+	}
+
+	void unsetJsonSchemaValidatorSupplier(JsonSchemaValidatorSupplier supplier) {
+		mcpValidatorServiceLoader.unsetSupplier(supplier);
+	}
+
+	public synchronized static JsonSchemaValidator getDefaultJsonSchemaValidator() {
+		if (mcpValidatorServiceLoader == null) {
+			new McpJsonDefaults();
+		}
+		return mcpValidatorServiceLoader.getDefault();
+	}
+
+}
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/json/McpJsonMapper.java b/mcp-core/src/main/java/io/modelcontextprotocol/json/McpJsonMapper.java
new file mode 100644
index 000000000..8481d1703
--- /dev/null
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/json/McpJsonMapper.java
@@ -0,0 +1,90 @@
+/*
+ * Copyright 2025 - 2025 the original author or authors.
+ */
+
+package io.modelcontextprotocol.json;
+
+import java.io.IOException;
+
+/**
+ * Abstraction for JSON serialization/deserialization to decouple the SDK from any
+ * specific JSON library. A default implementation backed by Jackson is provided in
+ * io.modelcontextprotocol.spec.json.jackson.JacksonJsonMapper.
+ */
+public interface McpJsonMapper {
+
+	/**
+	 * Deserialize JSON string into a target type.
+	 * @param content JSON as String
+	 * @param type target class
+	 * @return deserialized instance
+	 * @param <T> generic type
+	 * @throws IOException on parse errors
+	 */
+	<T> T readValue(String content, Class<T> type) throws IOException;
+
+	/**
+	 * Deserialize JSON bytes into a target type.
+	 * @param content JSON as bytes
+	 * @param type target class
+	 * @return deserialized instance
+	 * @param <T> generic type
+	 * @throws IOException on parse errors
+	 */
+	<T> T readValue(byte[] content, Class<T> type) throws IOException;
+
+	/**
+	 * Deserialize JSON string into a parameterized target type.
+	 * @param content JSON as String
+	 * @param type parameterized type reference
+	 * @return deserialized instance
+	 * @param <T> generic type
+	 * @throws IOException on parse errors
+	 */
+	<T> T readValue(String content, TypeRef<T> type) throws IOException;
+
+	/**
+	 * Deserialize JSON bytes into a parameterized target type.
+	 * @param content JSON as bytes
+	 * @param type parameterized type reference
+	 * @return deserialized instance
+	 * @param <T> generic type
+	 * @throws IOException on parse errors
+	 */
+	<T> T readValue(byte[] content, TypeRef<T> type) throws IOException;
+
+	/**
+	 * Convert a value to a given type, useful for mapping nested JSON structures.
+	 * @param fromValue source value
+	 * @param type target class
+	 * @return converted value
+	 * @param <T> generic type
+	 */
+	<T> T convertValue(Object fromValue, Class<T> type);
+
+	/**
+	 * Convert a value to a given parameterized type.
+	 * @param fromValue source value
+	 * @param type target type reference
+	 * @return converted value
+	 * @param <T> generic type
+	 */
+	<T> T convertValue(Object fromValue, TypeRef<T> type);
+
+	/**
+	 * Serialize an object to JSON string.
+	 * @param value object to serialize
+	 * @return JSON as String
+	 * @throws IOException on serialization errors
+	 */
+	String writeValueAsString(Object value) throws IOException;
+
+	/**
+	 * Serialize an object to JSON bytes.
+	 * @param value object to serialize
+	 * @return JSON as bytes
+	 * @throws IOException on serialization errors
+	 */
+	byte[] writeValueAsBytes(Object value) throws IOException;
+
+}
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/json/McpJsonMapperSupplier.java b/mcp-core/src/main/java/io/modelcontextprotocol/json/McpJsonMapperSupplier.java
new file mode 100644
index 000000000..619f96040
--- /dev/null
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/json/McpJsonMapperSupplier.java
@@ -0,0 +1,14 @@
+/*
+ * Copyright 2025 - 2025 the original author or authors.
+ */
+
+package io.modelcontextprotocol.json;
+
+import java.util.function.Supplier;
+
+/**
+ * Strategy interface for resolving a {@link McpJsonMapper}.
+ */
+public interface McpJsonMapperSupplier extends Supplier<McpJsonMapper> {
+
+}
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/json/TypeRef.java b/mcp-core/src/main/java/io/modelcontextprotocol/json/TypeRef.java
new file mode 100644
index 000000000..725513c66
--- /dev/null
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/json/TypeRef.java
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2025 - 2025 the original author or authors.
+ */
+
+package io.modelcontextprotocol.json;
+
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+
+/**
+ * Captures generic type information at runtime for parameterized JSON (de)serialization.
+ * Usage: TypeRef<List<Foo>> ref = new TypeRef<>(){};
+ */
+public abstract class TypeRef<T> {
+
+	private final Type type;
+
+	/**
+	 * Constructs a new TypeRef instance, capturing the generic type information of the
+	 * subclass. This constructor should be called from an anonymous subclass to capture
+	 * the actual type arguments. For example: <pre>
+	 * TypeRef&lt;List&lt;Foo&gt;&gt; ref = new TypeRef&lt;&gt;(){};
+	 * </pre>
+	 * @throws IllegalStateException if TypeRef is not subclassed with actual type
+	 * information
+	 */
+	protected TypeRef() {
+		Type superClass = getClass().getGenericSuperclass();
+		if (superClass instanceof Class) {
+			throw new IllegalStateException("TypeRef constructed without actual type information");
+		}
+		this.type = ((ParameterizedType) superClass).getActualTypeArguments()[0];
+	}
+
+	/**
+	 * Returns the captured type information.
+	 * @return the Type representing the actual type argument captured by this TypeRef
+	 * instance
+	 */
+	public Type getType() {
+		return type;
+	}
+
+}
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonMapperSupplier.java b/mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonMapperSupplier.java
new file mode 100644
index 000000000..b44cadc62
--- /dev/null
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonMapperSupplier.java
@@ -0,0 +1,40 @@
+package io.modelcontextprotocol.json.internal;
+
+import java.util.Optional;
+import java.util.ServiceConfigurationError;
+import java.util.ServiceLoader;
+
+import io.modelcontextprotocol.json.McpJsonMapper;
+import io.modelcontextprotocol.json.McpJsonMapperSupplier;
+
+public class DefaultMcpJsonMapperSupplier {
+
+	private static McpJsonMapperSupplier jsonMapperSupplier;
+
+	private static McpJsonMapper defaultJsonMapper;
+
+	void setMcpJsonMapperSupplier(McpJsonMapperSupplier supplier) {
+		jsonMapperSupplier = supplier;
+	}
+
+	void unsetMcpJsonMapperSupplier(McpJsonMapperSupplier supplier) {
+		jsonMapperSupplier = null;
+		defaultJsonMapper = null;
+	}
+
+	public synchronized static McpJsonMapper getDefaultMcpJsonMapper() {
+		if (defaultJsonMapper == null) {
+			if (jsonMapperSupplier == null) {
+				// Use serviceloader
+				Optional<McpJsonMapperSupplier> sl = ServiceLoader.load(McpJsonMapperSupplier.class).findFirst();
+				if (sl.isEmpty()) {
+					throw new ServiceConfigurationError("No JsonMapperSupplier available for creating McpJsonMapper");
+				}
+				jsonMapperSupplier = sl.get();
+			}
+			defaultJsonMapper = jsonMapperSupplier.get();
+		}
+		return defaultJsonMapper;
+	}
+
+}
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonSchemaValidatorSupplier.java b/mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonSchemaValidatorSupplier.java
new file mode 100644
index 000000000..cb9d46029
--- /dev/null
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonSchemaValidatorSupplier.java
@@ -0,0 +1,42 @@
+package io.modelcontextprotocol.json.internal;
+
+import java.util.Optional;
+import java.util.ServiceConfigurationError;
+import java.util.ServiceLoader;
+
+import io.modelcontextprotocol.json.schema.JsonSchemaValidator;
+import io.modelcontextprotocol.json.schema.JsonSchemaValidatorSupplier;
+
+public class DefaultMcpJsonSchemaValidatorSupplier {
+
+	private static JsonSchemaValidatorSupplier jsonSchemaValidatorSupplier;
+
+	private static JsonSchemaValidator defaultJsonSchemaValidator;
+
+	void setJsonSchemaValidatorSupplier(JsonSchemaValidatorSupplier supplier) {
+		jsonSchemaValidatorSupplier = supplier;
+	}
+
+	void unsetJsonSchemaValidatorSupplier(JsonSchemaValidatorSupplier supplier) {
+		jsonSchemaValidatorSupplier = null;
+		defaultJsonSchemaValidator = null;
+	}
+
+	public synchronized static JsonSchemaValidator getDefaultJsonSchemaValidator() {
+		if (defaultJsonSchemaValidator == null) {
+			if (jsonSchemaValidatorSupplier == null) {
+				// Use serviceloader
+				Optional<JsonSchemaValidatorSupplier> sl = ServiceLoader.load(JsonSchemaValidatorSupplier.class)
+					.findFirst();
+				if (sl.isEmpty()) {
+					throw new ServiceConfigurationError(
+							"No JsonSchemaValidatorSupplier available for creating JsonSchemaValidator");
+				}
+				jsonSchemaValidatorSupplier = sl.get();
+			}
+			defaultJsonSchemaValidator = jsonSchemaValidatorSupplier.get();
+		}
+		return defaultJsonSchemaValidator;
+	}
+
+}
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/json/schema/JsonSchemaValidator.java b/mcp-core/src/main/java/io/modelcontextprotocol/json/schema/JsonSchemaValidator.java
new file mode 100644
index 000000000..09fe604f4
--- /dev/null
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/json/schema/JsonSchemaValidator.java
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2024-2024 the original author or authors.
+ */
+package io.modelcontextprotocol.json.schema;
+
+import java.util.Map;
+
+/**
+ * Interface for validating structured content against a JSON schema. This interface
+ * defines a method to validate structured content based on the provided output schema.
+ *
+ * @author Christian Tzolov
+ */
+public interface JsonSchemaValidator {
+
+	/**
+	 * Represents the result of a validation operation.
+	 *
+	 * @param valid Indicates whether the validation was successful.
+	 * @param errorMessage An error message if the validation failed, otherwise null.
+	 * @param jsonStructuredOutput The text structured content in JSON format if the
+	 * validation was successful, otherwise null.
+	 */
+	record ValidationResponse(boolean valid, String errorMessage, String jsonStructuredOutput) {
+
+		public static ValidationResponse asValid(String jsonStructuredOutput) {
+			return new ValidationResponse(true, null, jsonStructuredOutput);
+		}
+
+		public static ValidationResponse asInvalid(String message) {
+			return new ValidationResponse(false, message, null);
+		}
+	}
+
+	/**
+	 * Validates the structured content against the provided JSON schema.
+	 * @param schema The JSON schema to validate against.
+	 * @param structuredContent The structured content to validate.
+	 * @return A ValidationResponse indicating whether the validation was successful or
+	 * not.
+	 */
+	ValidationResponse validate(Map<String, Object> schema, Object structuredContent);
+
+}
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/json/schema/JsonSchemaValidatorSupplier.java b/mcp-core/src/main/java/io/modelcontextprotocol/json/schema/JsonSchemaValidatorSupplier.java
new file mode 100644
index 000000000..6f69169a0
--- /dev/null
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/json/schema/JsonSchemaValidatorSupplier.java
@@ -0,0 +1,19 @@
+/*
+ * Copyright 2025 - 2025 the original author or authors.
+ */
+
+package io.modelcontextprotocol.json.schema;
+
+import java.util.function.Supplier;
+
+/**
+ * A supplier interface that provides a {@link JsonSchemaValidator} instance.
+ * Implementations of this interface are expected to return a new or cached instance of
+ * {@link JsonSchemaValidator} when {@link #get()} is invoked.
+ *
+ * @see JsonSchemaValidator
+ * @see Supplier
+ */
+public interface JsonSchemaValidatorSupplier extends Supplier<JsonSchemaValidator> {
+
+}
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/server/McpServer.java b/mcp-core/src/main/java/io/modelcontextprotocol/server/McpServer.java
index fe3125271..2e4026325 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/server/McpServer.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/server/McpServer.java
@@ -14,6 +14,7 @@
 import java.util.function.BiConsumer;
 import java.util.function.BiFunction;
 
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 
 import io.modelcontextprotocol.json.schema.JsonSchemaValidator;
@@ -240,10 +241,11 @@ public McpAsyncServer build() {
 					this.instructions);
 
 			var jsonSchemaValidator = (this.jsonSchemaValidator != null) ? this.jsonSchemaValidator
-					: JsonSchemaValidator.getDefault();
+					: McpJsonDefaults.getDefaultJsonSchemaValidator();
 
-			return new McpAsyncServer(transportProvider, jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper,
-					features, requestTimeout, uriTemplateManagerFactory, jsonSchemaValidator);
+			return new McpAsyncServer(transportProvider,
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, features,
+					requestTimeout, uriTemplateManagerFactory, jsonSchemaValidator);
 		}
 
 	}
@@ -267,9 +269,10 @@ public McpAsyncServer build() {
 					this.resources, this.resourceTemplates, this.prompts, this.completions, this.rootsChangeHandlers,
 					this.instructions);
 			var jsonSchemaValidator = this.jsonSchemaValidator != null ? this.jsonSchemaValidator
-					: JsonSchemaValidator.getDefault();
-			return new McpAsyncServer(transportProvider, jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper,
-					features, requestTimeout, uriTemplateManagerFactory, jsonSchemaValidator);
+					: McpJsonDefaults.getDefaultJsonSchemaValidator();
+			return new McpAsyncServer(transportProvider,
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, features,
+					requestTimeout, uriTemplateManagerFactory, jsonSchemaValidator);
 		}
 
 	}
@@ -834,9 +837,9 @@ public McpSyncServer build() {
 					this.immediateExecution);
 
 			var asyncServer = new McpAsyncServer(transportProvider,
-					jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper, asyncFeatures, requestTimeout,
-					uriTemplateManagerFactory,
-					jsonSchemaValidator != null ? jsonSchemaValidator : JsonSchemaValidator.getDefault());
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, asyncFeatures,
+					requestTimeout, uriTemplateManagerFactory, jsonSchemaValidator != null ? jsonSchemaValidator
+							: McpJsonDefaults.getDefaultJsonSchemaValidator());
 			return new McpSyncServer(asyncServer, this.immediateExecution);
 		}
 
@@ -864,10 +867,10 @@ public McpSyncServer build() {
 			McpServerFeatures.Async asyncFeatures = McpServerFeatures.Async.fromSync(syncFeatures,
 					this.immediateExecution);
 			var jsonSchemaValidator = this.jsonSchemaValidator != null ? this.jsonSchemaValidator
-					: JsonSchemaValidator.getDefault();
+					: McpJsonDefaults.getDefaultJsonSchemaValidator();
 			var asyncServer = new McpAsyncServer(transportProvider,
-					jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper, asyncFeatures, this.requestTimeout,
-					this.uriTemplateManagerFactory, jsonSchemaValidator);
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, asyncFeatures,
+					this.requestTimeout, this.uriTemplateManagerFactory, jsonSchemaValidator);
 			return new McpSyncServer(asyncServer, this.immediateExecution);
 		}
 
@@ -1871,9 +1874,10 @@ public StatelessAsyncSpecification jsonSchemaValidator(JsonSchemaValidator jsonS
 		public McpStatelessAsyncServer build() {
 			var features = new McpStatelessServerFeatures.Async(this.serverInfo, this.serverCapabilities, this.tools,
 					this.resources, this.resourceTemplates, this.prompts, this.completions, this.instructions);
-			return new McpStatelessAsyncServer(transport, jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper,
-					features, requestTimeout, uriTemplateManagerFactory,
-					jsonSchemaValidator != null ? jsonSchemaValidator : JsonSchemaValidator.getDefault());
+			return new McpStatelessAsyncServer(transport,
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, features,
+					requestTimeout, uriTemplateManagerFactory, jsonSchemaValidator != null ? jsonSchemaValidator
+							: McpJsonDefaults.getDefaultJsonSchemaValidator());
 		}
 
 	}
@@ -2351,9 +2355,9 @@ public McpStatelessSyncServer build() {
 					this.resources, this.resourceTemplates, this.prompts, this.completions, this.instructions);
 			var asyncFeatures = McpStatelessServerFeatures.Async.fromSync(syncFeatures, this.immediateExecution);
 			var asyncServer = new McpStatelessAsyncServer(transport,
-					jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper, asyncFeatures, requestTimeout,
-					uriTemplateManagerFactory,
-					this.jsonSchemaValidator != null ? this.jsonSchemaValidator : JsonSchemaValidator.getDefault());
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, asyncFeatures,
+					requestTimeout, uriTemplateManagerFactory, this.jsonSchemaValidator != null
+							? this.jsonSchemaValidator : McpJsonDefaults.getDefaultJsonSchemaValidator());
 			return new McpStatelessSyncServer(asyncServer, this.immediateExecution);
 		}
 
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java b/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java
index 96cebb74a..476aafafe 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java
@@ -15,6 +15,7 @@
 import java.util.concurrent.atomic.AtomicBoolean;
 
 import io.modelcontextprotocol.common.McpTransportContext;
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 import io.modelcontextprotocol.json.TypeRef;
 import io.modelcontextprotocol.server.McpTransportContextExtractor;
@@ -632,8 +633,8 @@ public HttpServletSseServerTransportProvider build() {
 				throw new IllegalStateException("MessageEndpoint must be set");
 			}
 			return new HttpServletSseServerTransportProvider(
-					jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper, baseUrl, messageEndpoint, sseEndpoint,
-					keepAliveInterval, contextExtractor);
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, baseUrl,
+					messageEndpoint, sseEndpoint, keepAliveInterval, contextExtractor);
 		}
 
 	}
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStatelessServerTransport.java b/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStatelessServerTransport.java
index 40767f416..ae74cf839 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStatelessServerTransport.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStatelessServerTransport.java
@@ -11,6 +11,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 
 import io.modelcontextprotocol.common.McpTransportContext;
@@ -296,8 +297,9 @@ public Builder contextExtractor(McpTransportContextExtractor<HttpServletRequest>
 		 */
 		public HttpServletStatelessServerTransport build() {
 			Assert.notNull(mcpEndpoint, "Message endpoint must be set");
-			return new HttpServletStatelessServerTransport(jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper,
-					mcpEndpoint, contextExtractor);
+			return new HttpServletStatelessServerTransport(
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, mcpEndpoint,
+					contextExtractor);
 		}
 
 	}
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java b/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java
index 34671c105..5ed308b0b 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java
@@ -28,6 +28,7 @@
 import io.modelcontextprotocol.spec.McpStreamableServerTransportProvider;
 import io.modelcontextprotocol.spec.ProtocolVersions;
 import io.modelcontextprotocol.util.Assert;
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 import io.modelcontextprotocol.util.KeepAliveScheduler;
 import jakarta.servlet.AsyncContext;
@@ -842,8 +843,8 @@ public Builder keepAliveInterval(Duration keepAliveInterval) {
 		public HttpServletStreamableServerTransportProvider build() {
 			Assert.notNull(this.mcpEndpoint, "MCP endpoint must be set");
 			return new HttpServletStreamableServerTransportProvider(
-					jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper, mcpEndpoint, disallowDelete,
-					contextExtractor, keepAliveInterval);
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, mcpEndpoint,
+					disallowDelete, contextExtractor, keepAliveInterval);
 		}
 
 	}
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/util/McpServiceLoader.java b/mcp-core/src/main/java/io/modelcontextprotocol/util/McpServiceLoader.java
new file mode 100644
index 000000000..e67ff46d3
--- /dev/null
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/util/McpServiceLoader.java
@@ -0,0 +1,50 @@
+package io.modelcontextprotocol.util;
+
+import java.util.Optional;
+import java.util.ServiceConfigurationError;
+import java.util.ServiceLoader;
+import java.util.function.Supplier;
+
+public class McpServiceLoader<S extends Supplier<R>, R> {
+
+	private Class<S> supplierType;
+
+	private S supplier;
+
+	private R supplierResult;
+
+	public void setSupplier(S supplier) {
+		this.supplier = supplier;
+		this.supplierResult = null;
+	}
+
+	public void unsetSupplier(S supplier) {
+		this.supplier = null;
+		this.supplierResult = null;
+	}
+
+	public McpServiceLoader(Class<S> supplierType) {
+		this.supplierType = supplierType;
+	}
+
+	protected Optional<S> serviceLoad(Class<S> type) {
+		return ServiceLoader.load(type).findFirst();
+	}
+
+	@SuppressWarnings("unchecked")
+	public synchronized R getDefault() {
+		if (this.supplierResult == null) {
+			if (this.supplier == null) {
+				// Use serviceloader
+				Optional<?> sl = serviceLoad(this.supplierType);
+				if (sl.isEmpty()) {
+					throw new ServiceConfigurationError("No JsonMapperSupplier available for creating McpJsonMapper");
+				}
+				this.supplier = (S) sl.get();
+			}
+			this.supplierResult = this.supplier.get();
+		}
+		return supplierResult;
+	}
+
+}
diff --git a/mcp-core/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.McpJsonDefaults.xml b/mcp-core/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.McpJsonDefaults.xml
new file mode 100644
index 000000000..1a10fdfb3
--- /dev/null
+++ b/mcp-core/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.McpJsonDefaults.xml
@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.3.0" name="io.modelcontextprotocol.json.McpJsonDefaults" immediate="true">
+  <service>
+    <provide interface="io.modelcontextprotocol.json.McpJsonDefaults"/>
+  </service>
+  <reference name="McpJsonMapperSupplier" interface="io.modelcontextprotocol.json.McpJsonMapperSupplier" bind="setMcpJsonMapperSupplier" unbind="unsetMcpJsonMapperSupplier"/>
+  <reference name="JsonSchemaValidatorSupplier" interface="io.modelcontextprotocol.json.schema.JsonSchemaValidatorSupplier" bind="setJsonSchemaValidatorSupplier" unbind="unsetJsonSchemaValidatorSupplier"/>
+  <implementation class="io.modelcontextprotocol.json.McpJsonDefaults"/>
+</scr:component>
diff --git a/mcp-core/src/test/java/io/modelcontextprotocol/MockMcpClientTransport.java b/mcp-core/src/test/java/io/modelcontextprotocol/MockMcpClientTransport.java
index 9854de210..04b058973 100644
--- a/mcp-core/src/test/java/io/modelcontextprotocol/MockMcpClientTransport.java
+++ b/mcp-core/src/test/java/io/modelcontextprotocol/MockMcpClientTransport.java
@@ -9,7 +9,7 @@
 import java.util.function.BiConsumer;
 import java.util.function.Function;
 
-import io.modelcontextprotocol.json.McpJsonMapper;
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.TypeRef;
 import io.modelcontextprotocol.spec.McpClientTransport;
 import io.modelcontextprotocol.spec.McpSchema;
@@ -100,7 +100,7 @@ public Mono<Void> closeGracefully() {
 
 	@Override
 	public <T> T unmarshalFrom(Object data, TypeRef<T> typeRef) {
-		return McpJsonMapper.getDefault().convertValue(data, typeRef);
+		return McpJsonDefaults.getDefaultMcpJsonMapper().convertValue(data, typeRef);
 	}
 
 }
diff --git a/mcp-core/src/test/java/io/modelcontextprotocol/MockMcpServerTransport.java b/mcp-core/src/test/java/io/modelcontextprotocol/MockMcpServerTransport.java
index f3d6b77a7..5fefb892d 100644
--- a/mcp-core/src/test/java/io/modelcontextprotocol/MockMcpServerTransport.java
+++ b/mcp-core/src/test/java/io/modelcontextprotocol/MockMcpServerTransport.java
@@ -8,7 +8,7 @@
 import java.util.List;
 import java.util.function.BiConsumer;
 
-import io.modelcontextprotocol.json.McpJsonMapper;
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.TypeRef;
 import io.modelcontextprotocol.spec.McpSchema;
 import io.modelcontextprotocol.spec.McpSchema.JSONRPCNotification;
@@ -68,7 +68,7 @@ public Mono<Void> closeGracefully() {
 
 	@Override
 	public <T> T unmarshalFrom(Object data, TypeRef<T> typeRef) {
-		return McpJsonMapper.getDefault().convertValue(data, typeRef);
+		return McpJsonDefaults.getDefaultMcpJsonMapper().convertValue(data, typeRef);
 	}
 
 }
diff --git a/mcp-core/src/test/java/io/modelcontextprotocol/spec/CompleteCompletionSerializationTest.java b/mcp-core/src/test/java/io/modelcontextprotocol/spec/CompleteCompletionSerializationTest.java
index 55f71fea4..da5422e4e 100644
--- a/mcp-core/src/test/java/io/modelcontextprotocol/spec/CompleteCompletionSerializationTest.java
+++ b/mcp-core/src/test/java/io/modelcontextprotocol/spec/CompleteCompletionSerializationTest.java
@@ -1,5 +1,6 @@
 package io.modelcontextprotocol.spec;
 
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 import org.junit.jupiter.api.Test;
 import java.io.IOException;
@@ -10,7 +11,7 @@ class CompleteCompletionSerializationTest {
 
 	@Test
 	void codeCompletionSerialization() throws IOException {
-		McpJsonMapper jsonMapper = McpJsonMapper.getDefault();
+		McpJsonMapper jsonMapper = McpJsonDefaults.getDefaultMcpJsonMapper();
 		McpSchema.CompleteResult.CompleteCompletion codeComplete = new McpSchema.CompleteResult.CompleteCompletion(
 				Collections.emptyList(), 0, false);
 		String json = jsonMapper.writeValueAsString(codeComplete);
diff --git a/mcp-core/src/test/java/io/modelcontextprotocol/util/McpJsonMapperUtils.java b/mcp-core/src/test/java/io/modelcontextprotocol/util/McpJsonMapperUtils.java
index 911506e01..0af4815c9 100644
--- a/mcp-core/src/test/java/io/modelcontextprotocol/util/McpJsonMapperUtils.java
+++ b/mcp-core/src/test/java/io/modelcontextprotocol/util/McpJsonMapperUtils.java
@@ -1,5 +1,6 @@
 package io.modelcontextprotocol.util;
 
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 
 public final class McpJsonMapperUtils {
@@ -7,6 +8,6 @@ public final class McpJsonMapperUtils {
 	private McpJsonMapperUtils() {
 	}
 
-	public static final McpJsonMapper JSON_MAPPER = McpJsonMapper.getDefault();
+	public static final McpJsonMapper JSON_MAPPER = McpJsonDefaults.getDefaultMcpJsonMapper();
 
 }
diff --git a/mcp-json-jackson2/pom.xml b/mcp-json-jackson2/pom.xml
index 956a72c23..37384fea9 100644
--- a/mcp-json-jackson2/pom.xml
+++ b/mcp-json-jackson2/pom.xml
@@ -10,7 +10,7 @@
 	</parent>
 	<artifactId>mcp-json-jackson2</artifactId>
 	<packaging>jar</packaging>
-	<name>Java MCP SDK JSON Jackson</name>
+	<name>Java MCP SDK JSON Jackson 2</name>
 	<description>Java MCP SDK JSON implementation based on Jackson 2</description>
 	<url>https://github.com/modelcontextprotocol/java-sdk</url>
 	<scm>
@@ -20,30 +20,59 @@
 	</scm>
 	<build>
 		<plugins>
+			<plugin>
+				<groupId>biz.aQute.bnd</groupId>
+				<artifactId>bnd-maven-plugin</artifactId>
+				<version>${bnd-maven-plugin.version}</version>
+				<executions>
+					<execution>
+						<id>bnd-process</id>
+						<goals>
+							<goal>bnd-process</goal>
+						</goals>
+						<configuration>
+							<bnd><![CDATA[
+								Bundle-Name:            Bundle ${project.groupId} : ${project.artifactId}
+								version:                ${versionmask;===;${version_cleanup;${project.version}}}
+								Bundle-SymbolicName:    ${project.groupId}.${project.artifactId}
+								Bundle-Version:         ${version}
+								Automatic-Module-Name:  ${project.groupId}.${project.artifactId}
+								Bundle-ActivationPolicy: lazy
+								Import-Package:         io.modelcontextprotocol.json,io.modelcontextprotocol.json.schema, \
+								                        *;
+								Service-Component: 		OSGI-INF/io.modelcontextprotocol.json.jackson2.JacksonMcpJsonMapperSupplier.xml,OSGI-INF/io.modelcontextprotocol.json.schema.jackson2.JacksonJsonSchemaValidatorSupplier.xml
+								-noimportjava:          true;
+								-nouses:                true;
+								-removeheaders:         Private-Package
+								]]>
+							</bnd>
+						</configuration>
+					</execution>
+				</executions>
+			</plugin>
+
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-jar-plugin</artifactId>
 				<configuration>
 					<archive>
-                        <manifest>
-                            <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
-                        </manifest>
+						<manifestFile>${project.build.outputDirectory}/META-INF/MANIFEST.MF</manifestFile>
 					</archive>
 				</configuration>
 			</plugin>
 		</plugins>
 	</build>
 	<dependencies>
-        <dependency>
-            <groupId>io.modelcontextprotocol.sdk</groupId>
-            <artifactId>mcp-json</artifactId>
-            <version>0.18.0-SNAPSHOT</version>
-        </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
             <version>${jackson2.version}</version>
         </dependency>
+        <dependency>
+        	<groupId>io.modelcontextprotocol.sdk</groupId>
+        	<artifactId>mcp-core</artifactId>
+        	<version>0.18.0-SNAPSHOT</version>
+        </dependency>
         <dependency>
             <groupId>com.networknt</groupId>
             <artifactId>json-schema-validator</artifactId>
diff --git a/mcp-json-jackson2/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.jackson2.JacksonMcpJsonMapperSupplier.xml b/mcp-json-jackson2/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.jackson2.JacksonMcpJsonMapperSupplier.xml
new file mode 100644
index 000000000..1d6705f56
--- /dev/null
+++ b/mcp-json-jackson2/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.jackson2.JacksonMcpJsonMapperSupplier.xml
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.3.0" name="io.modelcontextprotocol.json.jackson.JacksonMcpJsonMapperSupplier" immediate="true">
+  <service>
+    <provide interface="io.modelcontextprotocol.json.McpJsonMapperSupplier"/>
+  </service>
+  <implementation class="io.modelcontextprotocol.json.jackson2.JacksonMcpJsonMapperSupplier"/>
+</scr:component>
diff --git a/mcp-json-jackson2/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.schema.jackson2.JacksonJsonSchemaValidatorSupplier.xml b/mcp-json-jackson2/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.schema.jackson2.JacksonJsonSchemaValidatorSupplier.xml
new file mode 100644
index 000000000..ad628745f
--- /dev/null
+++ b/mcp-json-jackson2/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.schema.jackson2.JacksonJsonSchemaValidatorSupplier.xml
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.3.0" name="io.modelcontextprotocol.json.schema.jackson.JacksonJsonSchemaValidatorSupplier" immediate="true">
+  <service>
+    <provide interface="io.modelcontextprotocol.json.schema.JsonSchemaValidatorSupplier"/>
+  </service>
+  <implementation class="io.modelcontextprotocol.json.schema.jackson2.JacksonJsonSchemaValidatorSupplier"/>
+</scr:component>
diff --git a/mcp-json-jackson2/src/test/java/io/modelcontextprotocol/json/McpJsonMapperTest.java b/mcp-json-jackson2/src/test/java/io/modelcontextprotocol/json/McpJsonMapperTest.java
index 062927587..bf865a087 100644
--- a/mcp-json-jackson2/src/test/java/io/modelcontextprotocol/json/McpJsonMapperTest.java
+++ b/mcp-json-jackson2/src/test/java/io/modelcontextprotocol/json/McpJsonMapperTest.java
@@ -14,7 +14,7 @@ class McpJsonMapperTest {
 
 	@Test
 	void shouldUseJackson2Mapper() {
-		assertThat(McpJsonMapper.getDefault()).isInstanceOf(JacksonMcpJsonMapper.class);
+		assertThat(McpJsonDefaults.getDefaultMcpJsonMapper()).isInstanceOf(JacksonMcpJsonMapper.class);
 	}
 
 }
diff --git a/mcp-json-jackson2/src/test/java/io/modelcontextprotocol/json/schema/JsonSchemaValidatorTest.java b/mcp-json-jackson2/src/test/java/io/modelcontextprotocol/json/schema/JsonSchemaValidatorTest.java
index 7b92eb7ee..0c5864a2e 100644
--- a/mcp-json-jackson2/src/test/java/io/modelcontextprotocol/json/schema/JsonSchemaValidatorTest.java
+++ b/mcp-json-jackson2/src/test/java/io/modelcontextprotocol/json/schema/JsonSchemaValidatorTest.java
@@ -8,13 +8,14 @@
 
 import org.junit.jupiter.api.Test;
 
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.schema.jackson2.DefaultJsonSchemaValidator;
 
 class JsonSchemaValidatorTest {
 
 	@Test
 	void shouldUseJackson2Mapper() {
-		assertThat(JsonSchemaValidator.getDefault()).isInstanceOf(DefaultJsonSchemaValidator.class);
+		assertThat(McpJsonDefaults.getDefaultJsonSchemaValidator()).isInstanceOf(DefaultJsonSchemaValidator.class);
 	}
 
 }
diff --git a/mcp-json-jackson3/pom.xml b/mcp-json-jackson3/pom.xml
index a3cc47048..c02bc375b 100644
--- a/mcp-json-jackson3/pom.xml
+++ b/mcp-json-jackson3/pom.xml
@@ -10,7 +10,7 @@
 	</parent>
 	<artifactId>mcp-json-jackson3</artifactId>
 	<packaging>jar</packaging>
-	<name>Java MCP SDK JSON Jackson</name>
+	<name>Java MCP SDK JSON Jackson 3</name>
 	<description>Java MCP SDK JSON implementation based on Jackson 3</description>
 	<url>https://github.com/modelcontextprotocol/java-sdk</url>
 	<scm>
@@ -20,14 +20,42 @@
 	</scm>
 	<build>
 		<plugins>
+			<plugin>
+				<groupId>biz.aQute.bnd</groupId>
+				<artifactId>bnd-maven-plugin</artifactId>
+				<version>${bnd-maven-plugin.version}</version>
+				<executions>
+					<execution>
+						<id>bnd-process</id>
+						<goals>
+							<goal>bnd-process</goal>
+						</goals>
+						<configuration>
+							<bnd><![CDATA[
+								Bundle-Name:            Bundle ${project.groupId} : ${project.artifactId}
+								version:                ${versionmask;===;${version_cleanup;${project.version}}}
+								Bundle-SymbolicName:    ${project.groupId}.${project.artifactId}
+								Bundle-Version:         ${version}
+								Automatic-Module-Name:  ${project.groupId}.${project.artifactId}
+								Bundle-ActivationPolicy: lazy
+								Import-Package:         io.modelcontextprotocol.json,io.modelcontextprotocol.json.schema, \
+								                        *;
+								Service-Component: 		OSGI-INF/io.modelcontextprotocol.json.jackson3.JacksonMcpJsonMapperSupplier.xml,OSGI-INF/io.modelcontextprotocol.json.schema.jackson3.JacksonJsonSchemaValidatorSupplier.xml
+								-noimportjava:          true;
+								-nouses:                true;
+								-removeheaders:         Private-Package
+								]]>
+							</bnd>
+						</configuration>
+					</execution>
+				</executions>
+			</plugin>
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-jar-plugin</artifactId>
 				<configuration>
 					<archive>
-                        <manifest>
-                            <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
-                        </manifest>
+						<manifestFile>${project.build.outputDirectory}/META-INF/MANIFEST.MF</manifestFile>
 					</archive>
 				</configuration>
 			</plugin>
@@ -35,9 +63,9 @@
 	</build>
 	<dependencies>
         <dependency>
-            <groupId>io.modelcontextprotocol.sdk</groupId>
-            <artifactId>mcp-json</artifactId>
-            <version>0.18.0-SNAPSHOT</version>
+        	<groupId>io.modelcontextprotocol.sdk</groupId>
+        	<artifactId>mcp-core</artifactId>
+        	<version>0.18.0-SNAPSHOT</version>
         </dependency>
         <dependency>
             <groupId>tools.jackson.core</groupId>
diff --git a/mcp-json-jackson3/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.jackson3.JacksonMcpJsonMapperSupplier.xml b/mcp-json-jackson3/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.jackson3.JacksonMcpJsonMapperSupplier.xml
new file mode 100644
index 000000000..0ad8a7b42
--- /dev/null
+++ b/mcp-json-jackson3/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.jackson3.JacksonMcpJsonMapperSupplier.xml
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.3.0" name="io.modelcontextprotocol.json.jackson.JacksonMcpJsonMapperSupplier" immediate="true">
+  <service>
+    <provide interface="io.modelcontextprotocol.json.McpJsonMapperSupplier"/>
+  </service>
+  <implementation class="io.modelcontextprotocol.json.jackson3.JacksonMcpJsonMapperSupplier"/>
+</scr:component>
diff --git a/mcp-json-jackson3/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.schema.jackson3.JacksonJsonSchemaValidatorSupplier.xml b/mcp-json-jackson3/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.schema.jackson3.JacksonJsonSchemaValidatorSupplier.xml
new file mode 100644
index 000000000..d14d8bea3
--- /dev/null
+++ b/mcp-json-jackson3/src/main/resources/OSGI-INF/io.modelcontextprotocol.json.schema.jackson3.JacksonJsonSchemaValidatorSupplier.xml
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.3.0" name="io.modelcontextprotocol.json.schema.jackson.JacksonJsonSchemaValidatorSupplier" immediate="true">
+  <service>
+    <provide interface="io.modelcontextprotocol.json.schema.JsonSchemaValidatorSupplier"/>
+  </service>
+  <implementation class="io.modelcontextprotocol.json.schema.jackson3.JacksonJsonSchemaValidatorSupplier"/>
+</scr:component>
diff --git a/mcp-json-jackson3/src/test/java/io/modelcontextprotocol/json/McpJsonMapperTest.java b/mcp-json-jackson3/src/test/java/io/modelcontextprotocol/json/McpJsonMapperTest.java
index e2d0a1d55..58f7e01dc 100644
--- a/mcp-json-jackson3/src/test/java/io/modelcontextprotocol/json/McpJsonMapperTest.java
+++ b/mcp-json-jackson3/src/test/java/io/modelcontextprotocol/json/McpJsonMapperTest.java
@@ -14,7 +14,7 @@ class McpJsonMapperTest {
 
 	@Test
 	void shouldUseJackson2Mapper() {
-		assertThat(McpJsonMapper.getDefault()).isInstanceOf(JacksonMcpJsonMapper.class);
+		assertThat(McpJsonDefaults.getDefaultMcpJsonMapper()).isInstanceOf(JacksonMcpJsonMapper.class);
 	}
 
 }
diff --git a/mcp-json-jackson3/src/test/java/io/modelcontextprotocol/json/schema/JsonSchemaValidatorTest.java b/mcp-json-jackson3/src/test/java/io/modelcontextprotocol/json/schema/JsonSchemaValidatorTest.java
index 29c450d40..89197579b 100644
--- a/mcp-json-jackson3/src/test/java/io/modelcontextprotocol/json/schema/JsonSchemaValidatorTest.java
+++ b/mcp-json-jackson3/src/test/java/io/modelcontextprotocol/json/schema/JsonSchemaValidatorTest.java
@@ -8,13 +8,14 @@
 
 import org.junit.jupiter.api.Test;
 
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.schema.jackson3.DefaultJsonSchemaValidator;
 
 class JsonSchemaValidatorTest {
 
 	@Test
 	void shouldUseJackson2Mapper() {
-		assertThat(JsonSchemaValidator.getDefault()).isInstanceOf(DefaultJsonSchemaValidator.class);
+		assertThat(McpJsonDefaults.getDefaultJsonSchemaValidator()).isInstanceOf(DefaultJsonSchemaValidator.class);
 	}
 
 }
diff --git a/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java b/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java
index 5af98985d..f5b6ead89 100644
--- a/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java
+++ b/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java
@@ -25,6 +25,7 @@
 import org.springframework.web.reactive.function.client.WebClientResponseException;
 
 import io.modelcontextprotocol.client.McpAsyncClient;
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 import io.modelcontextprotocol.json.TypeRef;
 import io.modelcontextprotocol.spec.ClosedMcpTransportSession;
@@ -615,8 +616,9 @@ public Builder supportedProtocolVersions(List<String> supportedProtocolVersions)
 		 * @return a new instance of {@link WebClientStreamableHttpTransport}
 		 */
 		public WebClientStreamableHttpTransport build() {
-			return new WebClientStreamableHttpTransport(jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper,
-					webClientBuilder, endpoint, resumableStreams, openConnectionOnStartup, supportedProtocolVersions);
+			return new WebClientStreamableHttpTransport(
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, webClientBuilder,
+					endpoint, resumableStreams, openConnectionOnStartup, supportedProtocolVersions);
 		}
 
 	}
diff --git a/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebFluxSseClientTransport.java b/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebFluxSseClientTransport.java
index 91b89d6d2..3c3a008b1 100644
--- a/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebFluxSseClientTransport.java
+++ b/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebFluxSseClientTransport.java
@@ -9,6 +9,7 @@
 import java.util.function.BiConsumer;
 import java.util.function.Function;
 
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 import io.modelcontextprotocol.json.TypeRef;
 
@@ -404,7 +405,7 @@ public Builder jsonMapper(McpJsonMapper jsonMapper) {
 		 */
 		public WebFluxSseClientTransport build() {
 			return new WebFluxSseClientTransport(webClientBuilder,
-					jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper, sseEndpoint);
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, sseEndpoint);
 		}
 
 	}
diff --git a/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/server/transport/WebFluxSseServerTransportProvider.java b/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/server/transport/WebFluxSseServerTransportProvider.java
index 0c80c5b8b..b7b4f22a6 100644
--- a/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/server/transport/WebFluxSseServerTransportProvider.java
+++ b/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/server/transport/WebFluxSseServerTransportProvider.java
@@ -10,6 +10,7 @@
 import java.util.concurrent.ConcurrentHashMap;
 
 import io.modelcontextprotocol.common.McpTransportContext;
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 import io.modelcontextprotocol.json.TypeRef;
 import io.modelcontextprotocol.server.McpTransportContextExtractor;
@@ -521,8 +522,9 @@ public Builder contextExtractor(McpTransportContextExtractor<ServerRequest> cont
 		 */
 		public WebFluxSseServerTransportProvider build() {
 			Assert.notNull(messageEndpoint, "Message endpoint must be set");
-			return new WebFluxSseServerTransportProvider(jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper,
-					baseUrl, messageEndpoint, sseEndpoint, keepAliveInterval, contextExtractor);
+			return new WebFluxSseServerTransportProvider(
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, baseUrl,
+					messageEndpoint, sseEndpoint, keepAliveInterval, contextExtractor);
 		}
 
 	}
diff --git a/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/server/transport/WebFluxStatelessServerTransport.java b/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/server/transport/WebFluxStatelessServerTransport.java
index 400be341e..78af45642 100644
--- a/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/server/transport/WebFluxStatelessServerTransport.java
+++ b/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/server/transport/WebFluxStatelessServerTransport.java
@@ -4,6 +4,7 @@
 
 package io.modelcontextprotocol.server.transport;
 
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 import io.modelcontextprotocol.common.McpTransportContext;
 import io.modelcontextprotocol.server.McpStatelessServerHandler;
@@ -213,8 +214,9 @@ public Builder contextExtractor(McpTransportContextExtractor<ServerRequest> cont
 		 */
 		public WebFluxStatelessServerTransport build() {
 			Assert.notNull(mcpEndpoint, "Message endpoint must be set");
-			return new WebFluxStatelessServerTransport(jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper,
-					mcpEndpoint, contextExtractor);
+			return new WebFluxStatelessServerTransport(
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, mcpEndpoint,
+					contextExtractor);
 		}
 
 	}
diff --git a/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/server/transport/WebFluxStreamableServerTransportProvider.java b/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/server/transport/WebFluxStreamableServerTransportProvider.java
index deebfc616..db171fe50 100644
--- a/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/server/transport/WebFluxStreamableServerTransportProvider.java
+++ b/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/server/transport/WebFluxStreamableServerTransportProvider.java
@@ -4,6 +4,7 @@
 
 package io.modelcontextprotocol.server.transport;
 
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 import io.modelcontextprotocol.json.TypeRef;
 import io.modelcontextprotocol.common.McpTransportContext;
@@ -486,8 +487,8 @@ public Builder keepAliveInterval(Duration keepAliveInterval) {
 		public WebFluxStreamableServerTransportProvider build() {
 			Assert.notNull(mcpEndpoint, "Message endpoint must be set");
 			return new WebFluxStreamableServerTransportProvider(
-					jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper, mcpEndpoint, contextExtractor,
-					disallowDelete, keepAliveInterval);
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, mcpEndpoint,
+					contextExtractor, disallowDelete, keepAliveInterval);
 		}
 
 	}
diff --git a/mcp-spring/mcp-spring-webflux/src/test/java/io/modelcontextprotocol/utils/McpJsonMapperUtils.java b/mcp-spring/mcp-spring-webflux/src/test/java/io/modelcontextprotocol/utils/McpJsonMapperUtils.java
index 67347573c..0177932cc 100644
--- a/mcp-spring/mcp-spring-webflux/src/test/java/io/modelcontextprotocol/utils/McpJsonMapperUtils.java
+++ b/mcp-spring/mcp-spring-webflux/src/test/java/io/modelcontextprotocol/utils/McpJsonMapperUtils.java
@@ -1,5 +1,6 @@
 package io.modelcontextprotocol.utils;
 
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 
 public final class McpJsonMapperUtils {
@@ -7,6 +8,6 @@ public final class McpJsonMapperUtils {
 	private McpJsonMapperUtils() {
 	}
 
-	public static final McpJsonMapper JSON_MAPPER = McpJsonMapper.createDefault();
+	public static final McpJsonMapper JSON_MAPPER = McpJsonDefaults.getDefaultMcpJsonMapper();
 
 }
\ No newline at end of file
diff --git a/mcp-spring/mcp-spring-webmvc/src/main/java/io/modelcontextprotocol/server/transport/WebMvcSseServerTransportProvider.java b/mcp-spring/mcp-spring-webmvc/src/main/java/io/modelcontextprotocol/server/transport/WebMvcSseServerTransportProvider.java
index 6c35de56d..2a29075ae 100644
--- a/mcp-spring/mcp-spring-webmvc/src/main/java/io/modelcontextprotocol/server/transport/WebMvcSseServerTransportProvider.java
+++ b/mcp-spring/mcp-spring-webmvc/src/main/java/io/modelcontextprotocol/server/transport/WebMvcSseServerTransportProvider.java
@@ -11,6 +11,7 @@
 import java.util.concurrent.locks.ReentrantLock;
 
 import io.modelcontextprotocol.common.McpTransportContext;
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 import io.modelcontextprotocol.json.TypeRef;
 import io.modelcontextprotocol.server.McpTransportContextExtractor;
@@ -559,8 +560,9 @@ public WebMvcSseServerTransportProvider build() {
 			if (messageEndpoint == null) {
 				throw new IllegalStateException("MessageEndpoint must be set");
 			}
-			return new WebMvcSseServerTransportProvider(jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper,
-					baseUrl, messageEndpoint, sseEndpoint, keepAliveInterval, contextExtractor);
+			return new WebMvcSseServerTransportProvider(
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, baseUrl,
+					messageEndpoint, sseEndpoint, keepAliveInterval, contextExtractor);
 		}
 
 	}
diff --git a/mcp-spring/mcp-spring-webmvc/src/main/java/io/modelcontextprotocol/server/transport/WebMvcStatelessServerTransport.java b/mcp-spring/mcp-spring-webmvc/src/main/java/io/modelcontextprotocol/server/transport/WebMvcStatelessServerTransport.java
index 67b5f571c..244b17e59 100644
--- a/mcp-spring/mcp-spring-webmvc/src/main/java/io/modelcontextprotocol/server/transport/WebMvcStatelessServerTransport.java
+++ b/mcp-spring/mcp-spring-webmvc/src/main/java/io/modelcontextprotocol/server/transport/WebMvcStatelessServerTransport.java
@@ -5,6 +5,7 @@
 package io.modelcontextprotocol.server.transport;
 
 import io.modelcontextprotocol.common.McpTransportContext;
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 import io.modelcontextprotocol.server.McpStatelessServerHandler;
 import io.modelcontextprotocol.server.McpTransportContextExtractor;
@@ -232,8 +233,9 @@ public Builder contextExtractor(McpTransportContextExtractor<ServerRequest> cont
 		 */
 		public WebMvcStatelessServerTransport build() {
 			Assert.notNull(mcpEndpoint, "Message endpoint must be set");
-			return new WebMvcStatelessServerTransport(jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper,
-					mcpEndpoint, contextExtractor);
+			return new WebMvcStatelessServerTransport(
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, mcpEndpoint,
+					contextExtractor);
 		}
 
 	}
diff --git a/mcp-spring/mcp-spring-webmvc/src/main/java/io/modelcontextprotocol/server/transport/WebMvcStreamableServerTransportProvider.java b/mcp-spring/mcp-spring-webmvc/src/main/java/io/modelcontextprotocol/server/transport/WebMvcStreamableServerTransportProvider.java
index f2a58d4d8..8d54fd25b 100644
--- a/mcp-spring/mcp-spring-webmvc/src/main/java/io/modelcontextprotocol/server/transport/WebMvcStreamableServerTransportProvider.java
+++ b/mcp-spring/mcp-spring-webmvc/src/main/java/io/modelcontextprotocol/server/transport/WebMvcStreamableServerTransportProvider.java
@@ -10,6 +10,7 @@
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.locks.ReentrantLock;
 
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -681,8 +682,8 @@ public Builder keepAliveInterval(Duration keepAliveInterval) {
 		public WebMvcStreamableServerTransportProvider build() {
 			Assert.notNull(this.mcpEndpoint, "MCP endpoint must be set");
 			return new WebMvcStreamableServerTransportProvider(
-					jsonMapper == null ? McpJsonMapper.getDefault() : jsonMapper, mcpEndpoint, disallowDelete,
-					contextExtractor, keepAliveInterval);
+					jsonMapper == null ? McpJsonDefaults.getDefaultMcpJsonMapper() : jsonMapper, mcpEndpoint,
+					disallowDelete, contextExtractor, keepAliveInterval);
 		}
 
 	}
diff --git a/mcp-spring/mcp-spring-webmvc/src/test/java/io/modelcontextprotocol/server/transport/WebMvcSseServerTransportProviderTests.java b/mcp-spring/mcp-spring-webmvc/src/test/java/io/modelcontextprotocol/server/transport/WebMvcSseServerTransportProviderTests.java
index 1074e8a35..36ea2d354 100644
--- a/mcp-spring/mcp-spring-webmvc/src/test/java/io/modelcontextprotocol/server/transport/WebMvcSseServerTransportProviderTests.java
+++ b/mcp-spring/mcp-spring-webmvc/src/test/java/io/modelcontextprotocol/server/transport/WebMvcSseServerTransportProviderTests.java
@@ -7,6 +7,7 @@
 import io.modelcontextprotocol.client.McpClient;
 import io.modelcontextprotocol.client.transport.HttpClientSseClientTransport;
 import io.modelcontextprotocol.common.McpTransportContext;
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 import io.modelcontextprotocol.server.McpServer;
 import io.modelcontextprotocol.server.TestUtil;
@@ -104,7 +105,7 @@ public WebMvcSseServerTransportProvider webMvcSseServerTransportProvider() {
 				.baseUrl("http://localhost:" + PORT + "/")
 				.messageEndpoint(MESSAGE_ENDPOINT)
 				.sseEndpoint(WebMvcSseServerTransportProvider.DEFAULT_SSE_ENDPOINT)
-				.jsonMapper(McpJsonMapper.getDefault())
+				.jsonMapper(McpJsonDefaults.getDefaultMcpJsonMapper())
 				.contextExtractor(req -> McpTransportContext.EMPTY)
 				.build();
 		}
diff --git a/mcp-test/src/main/java/io/modelcontextprotocol/MockMcpTransport.java b/mcp-test/src/main/java/io/modelcontextprotocol/MockMcpTransport.java
index cd8458311..7d71376b4 100644
--- a/mcp-test/src/main/java/io/modelcontextprotocol/MockMcpTransport.java
+++ b/mcp-test/src/main/java/io/modelcontextprotocol/MockMcpTransport.java
@@ -9,7 +9,7 @@
 import java.util.function.BiConsumer;
 import java.util.function.Function;
 
-import io.modelcontextprotocol.json.McpJsonMapper;
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.TypeRef;
 import io.modelcontextprotocol.spec.McpClientTransport;
 import io.modelcontextprotocol.spec.McpSchema;
@@ -94,7 +94,7 @@ public Mono<Void> closeGracefully() {
 
 	@Override
 	public <T> T unmarshalFrom(Object data, TypeRef<T> typeRef) {
-		return McpJsonMapper.getDefault().convertValue(data, typeRef);
+		return McpJsonDefaults.getDefaultMcpJsonMapper().convertValue(data, typeRef);
 	}
 
 }
diff --git a/mcp-test/src/main/java/io/modelcontextprotocol/util/McpJsonMapperUtils.java b/mcp-test/src/main/java/io/modelcontextprotocol/util/McpJsonMapperUtils.java
index 723965519..45e4a4e3c 100644
--- a/mcp-test/src/main/java/io/modelcontextprotocol/util/McpJsonMapperUtils.java
+++ b/mcp-test/src/main/java/io/modelcontextprotocol/util/McpJsonMapperUtils.java
@@ -1,5 +1,6 @@
 package io.modelcontextprotocol.util;
 
+import io.modelcontextprotocol.json.McpJsonDefaults;
 import io.modelcontextprotocol.json.McpJsonMapper;
 
 public final class McpJsonMapperUtils {
@@ -7,6 +8,6 @@ public final class McpJsonMapperUtils {
 	private McpJsonMapperUtils() {
 	}
 
-	public static final McpJsonMapper JSON_MAPPER = McpJsonMapper.getDefault();
+	public static final McpJsonMapper JSON_MAPPER = McpJsonDefaults.getDefaultMcpJsonMapper();
 
 }
\ No newline at end of file
diff --git a/pom.xml b/pom.xml
index faa2ad86e..f25f49275 100644
--- a/pom.xml
+++ b/pom.xml
@@ -109,7 +109,6 @@
         <module>mcp-core</module>
         <module>mcp-json-jackson2</module>
         <module>mcp-json-jackson3</module>
-        <module>mcp-json</module>
 		<module>mcp-spring/mcp-spring-webflux</module>
 		<module>mcp-spring/mcp-spring-webmvc</module>
 		<module>mcp-test</module>

From bedf075f56c182477e4539753bfddc0c756a91fc Mon Sep 17 00:00:00 2001
From: Scott Lewis <scottslewis@gmail.com>
Date: Thu, 29 Jan 2026 13:43:00 -0800
Subject: [PATCH 2/4] Fix for missing <scope>test</scope> in mcp-core.  Thanks
 to @lucabutboring for catch

---
 mcp-core/pom.xml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mcp-core/pom.xml b/mcp-core/pom.xml
index 989764873..1db05f9e4 100644
--- a/mcp-core/pom.xml
+++ b/mcp-core/pom.xml
@@ -103,6 +103,7 @@
             <groupId>tools.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
             <version>${jackson3.version}</version>
+            <scope>test</scope>
         </dependency>
 
 		<dependency>

From fbda61f3bc7cc39a25722d15ea95f534352298e4 Mon Sep 17 00:00:00 2001
From: Scott Lewis <scottslewis@gmail.com>
Date: Thu, 29 Jan 2026 13:46:35 -0800
Subject: [PATCH 3/4] Update
 mcp-core/src/main/java/io/modelcontextprotocol/util/McpServiceLoader.java

Co-authored-by: Luca Chang <131398524+LucaButBoring@users.noreply.github.com>
---
 .../java/io/modelcontextprotocol/util/McpServiceLoader.java     | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/util/McpServiceLoader.java b/mcp-core/src/main/java/io/modelcontextprotocol/util/McpServiceLoader.java
index e67ff46d3..fd8fd8a14 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/util/McpServiceLoader.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/util/McpServiceLoader.java
@@ -38,7 +38,7 @@ public synchronized R getDefault() {
 				// Use serviceloader
 				Optional<?> sl = serviceLoad(this.supplierType);
 				if (sl.isEmpty()) {
-					throw new ServiceConfigurationError("No JsonMapperSupplier available for creating McpJsonMapper");
+					throw new ServiceConfigurationError("No %s available for creating McpJsonMapper".format(this.supplierType.getSimpleName()));
 				}
 				this.supplier = (S) sl.get();
 			}

From 76ce84df4e7fdf1548a701777e914897429e3742 Mon Sep 17 00:00:00 2001
From: Scott Lewis <scottslewis@gmail.com>
Date: Thu, 29 Jan 2026 14:14:56 -0800
Subject: [PATCH 4/4] Removed DefaultMcpJsonMapperSupplier

and DefaultMcpJsonSchemaSupplier as they were originally committed
accidently.  Thanks to LucaButBoring for pointing out the error.
---
 .../DefaultMcpJsonMapperSupplier.java         | 40 ------------------
 ...DefaultMcpJsonSchemaValidatorSupplier.java | 42 -------------------
 2 files changed, 82 deletions(-)
 delete mode 100644 mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonMapperSupplier.java
 delete mode 100644 mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonSchemaValidatorSupplier.java

diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonMapperSupplier.java b/mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonMapperSupplier.java
deleted file mode 100644
index b44cadc62..000000000
--- a/mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonMapperSupplier.java
+++ /dev/null
@@ -1,40 +0,0 @@
-package io.modelcontextprotocol.json.internal;
-
-import java.util.Optional;
-import java.util.ServiceConfigurationError;
-import java.util.ServiceLoader;
-
-import io.modelcontextprotocol.json.McpJsonMapper;
-import io.modelcontextprotocol.json.McpJsonMapperSupplier;
-
-public class DefaultMcpJsonMapperSupplier {
-
-	private static McpJsonMapperSupplier jsonMapperSupplier;
-
-	private static McpJsonMapper defaultJsonMapper;
-
-	void setMcpJsonMapperSupplier(McpJsonMapperSupplier supplier) {
-		jsonMapperSupplier = supplier;
-	}
-
-	void unsetMcpJsonMapperSupplier(McpJsonMapperSupplier supplier) {
-		jsonMapperSupplier = null;
-		defaultJsonMapper = null;
-	}
-
-	public synchronized static McpJsonMapper getDefaultMcpJsonMapper() {
-		if (defaultJsonMapper == null) {
-			if (jsonMapperSupplier == null) {
-				// Use serviceloader
-				Optional<McpJsonMapperSupplier> sl = ServiceLoader.load(McpJsonMapperSupplier.class).findFirst();
-				if (sl.isEmpty()) {
-					throw new ServiceConfigurationError("No JsonMapperSupplier available for creating McpJsonMapper");
-				}
-				jsonMapperSupplier = sl.get();
-			}
-			defaultJsonMapper = jsonMapperSupplier.get();
-		}
-		return defaultJsonMapper;
-	}
-
-}
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonSchemaValidatorSupplier.java b/mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonSchemaValidatorSupplier.java
deleted file mode 100644
index cb9d46029..000000000
--- a/mcp-core/src/main/java/io/modelcontextprotocol/json/internal/DefaultMcpJsonSchemaValidatorSupplier.java
+++ /dev/null
@@ -1,42 +0,0 @@
-package io.modelcontextprotocol.json.internal;
-
-import java.util.Optional;
-import java.util.ServiceConfigurationError;
-import java.util.ServiceLoader;
-
-import io.modelcontextprotocol.json.schema.JsonSchemaValidator;
-import io.modelcontextprotocol.json.schema.JsonSchemaValidatorSupplier;
-
-public class DefaultMcpJsonSchemaValidatorSupplier {
-
-	private static JsonSchemaValidatorSupplier jsonSchemaValidatorSupplier;
-
-	private static JsonSchemaValidator defaultJsonSchemaValidator;
-
-	void setJsonSchemaValidatorSupplier(JsonSchemaValidatorSupplier supplier) {
-		jsonSchemaValidatorSupplier = supplier;
-	}
-
-	void unsetJsonSchemaValidatorSupplier(JsonSchemaValidatorSupplier supplier) {
-		jsonSchemaValidatorSupplier = null;
-		defaultJsonSchemaValidator = null;
-	}
-
-	public synchronized static JsonSchemaValidator getDefaultJsonSchemaValidator() {
-		if (defaultJsonSchemaValidator == null) {
-			if (jsonSchemaValidatorSupplier == null) {
-				// Use serviceloader
-				Optional<JsonSchemaValidatorSupplier> sl = ServiceLoader.load(JsonSchemaValidatorSupplier.class)
-					.findFirst();
-				if (sl.isEmpty()) {
-					throw new ServiceConfigurationError(
-							"No JsonSchemaValidatorSupplier available for creating JsonSchemaValidator");
-				}
-				jsonSchemaValidatorSupplier = sl.get();
-			}
-			defaultJsonSchemaValidator = jsonSchemaValidatorSupplier.get();
-		}
-		return defaultJsonSchemaValidator;
-	}
-
-}