fix(config): Add version mismatch warning for declarative config

sdk-extensions/incubator/src/main/java/io/opentelemetry/sdk/extension/incubator/fileconfig/OpenTelemetryConfigurationFactory.java

@@ -16,12 +16,16 @@
 import io.opentelemetry.sdk.metrics.SdkMeterProvider;
 import io.opentelemetry.sdk.resources.Resource;
 import java.util.Objects;
+import java.util.logging.Logger;
 import java.util.regex.Pattern;
 
 final class OpenTelemetryConfigurationFactory
     implements Factory<OpenTelemetryConfigurationModel, ExtendedOpenTelemetrySdk> {
 
+  private static final Logger logger =
+      Logger.getLogger(OpenTelemetryConfigurationFactory.class.getName());
   private static final Pattern SUPPORTED_FILE_FORMATS = Pattern.compile("^(0.4)|(1.0(-rc.\\d*)?)$");
+  private static final String EXPECTED_FILE_FORMAT = "1.0-rc.3";
 
   private static final OpenTelemetryConfigurationFactory INSTANCE =
       new OpenTelemetryConfigurationFactory();
@@ -47,8 +51,14 @@ public ExtendedOpenTelemetrySdk create(
       throw new DeclarativeConfigException(
           "Unsupported file format '" + fileFormat + "'. Supported formats include 0.4, 1.0*");
     }
-    // TODO(jack-berg): log warning if version is not exact match, which may result in unexpected
-    // behavior for experimental properties.
+    if (!EXPECTED_FILE_FORMAT.equals(fileFormat)) {
+      logger.warning(
+          "Configuration file_format '"
+              + fileFormat
+              + "' does not exactly match expected version '"
+              + EXPECTED_FILE_FORMAT
+              + "'. This may result in unexpected behavior for experimental properties.");
+    }
 
     if (Objects.equals(true, model.getDisabled())) {
       return (ExtendedOpenTelemetrySdk) builder.build();

sdk-extensions/incubator/src/test/java/io/opentelemetry/sdk/extension/incubator/fileconfig/OpenTelemetryConfigurationFactoryTest.java

@@ -10,6 +10,7 @@
 import static org.assertj.core.api.Assertions.assertThatCode;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
+import io.github.netmikey.logunit.api.LogCapturer;
 import io.opentelemetry.api.baggage.propagation.W3CBaggagePropagator;
 import io.opentelemetry.api.incubator.config.DeclarativeConfigException;
 import io.opentelemetry.api.trace.propagation.W3CTraceContextPropagator;
@@ -72,11 +73,17 @@
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
+import org.slf4j.event.Level;
 
 class OpenTelemetryConfigurationFactoryTest {
 
   @RegisterExtension CleanupExtension cleanup = new CleanupExtension();
 
+  @RegisterExtension
+  LogCapturer logCapturer =
+      LogCapturer.create()
+          .captureForLogger(OpenTelemetryConfigurationFactory.class.getName(), Level.WARN);
+
   private final DeclarativeConfigContext context =
       new DeclarativeConfigContext(
           SpiHelper.create(OpenTelemetryConfigurationFactoryTest.class.getClassLoader()));
@@ -110,6 +117,7 @@ private static Stream<Arguments> fileFormatArgs() {
         Arguments.of("1.0-rc.a", false),
         Arguments.of("1.0.0", false),
         Arguments.of("1.0.3", false),
+        Arguments.of("1.0.0-rc.3", false),
         // Valid file formats
         Arguments.of("0.4", true),
         Arguments.of("1.0-rc.1", true),
@@ -118,6 +126,31 @@ private static Stream<Arguments> fileFormatArgs() {
         Arguments.of("1.0", true));
   }
 
+  @Test
+  void create_FileFormatVersionMismatch_LogsWarning() {
+    OpenTelemetryConfigurationModel model =
+        new OpenTelemetryConfigurationModel().withFileFormat("1.0-rc.2");
+
+    ExtendedOpenTelemetrySdk sdk =
+        OpenTelemetryConfigurationFactory.getInstance().create(model, context);
+    cleanup.addCloseable(sdk);
+
+    logCapturer.assertContains(
+        "Configuration file_format '1.0-rc.2' does not exactly match expected version '1.0-rc.3'");
+  }
+
+  @Test
+  void create_FileFormatExactMatch_NoWarning() {
+    OpenTelemetryConfigurationModel model =
+        new OpenTelemetryConfigurationModel().withFileFormat("1.0-rc.3");
+
+    ExtendedOpenTelemetrySdk sdk =
+        OpenTelemetryConfigurationFactory.getInstance().create(model, context);
+    cleanup.addCloseable(sdk);
+
+    assertThat(logCapturer.size()).isEqualTo(0);
+  }
+
   @Test
   void create_Defaults() {
     List<Closeable> closeables = new ArrayList<>();