[AI-FSSDK] [FSSDK-12337] Return Variation entity from _get_everyone_else_variation

- Build Variation entity once in helper, derive dict from it in caller
- Addresses PR review comment from jaeopt

Author: FarhanAnjum-opti

optimizely/project_config.py

@@ -238,26 +238,29 @@ def __init__(self, datafile: str | bytes, logger: Logger, error_handler: Any):
             if everyone_else_variation is not None:
                 for experiment in rules:
                     if experiment.type == 'feature_rollout':
-                        experiment.variations.append(everyone_else_variation)
+                        experiment.variations.append({
+                            'id': everyone_else_variation.id,
+                            'key': everyone_else_variation.key,
+                            'featureEnabled': everyone_else_variation.featureEnabled,
+                            'variables': cast(
+                                list[types.VariableDict],
+                                everyone_else_variation.variables,
+                            ),
+                        })
                         experiment.trafficAllocation.append({
-                            'entityId': everyone_else_variation['id'],
+                            'entityId': everyone_else_variation.id,
                             'endOfRange': 10000,
                         })
-                        var_entity = entities.Variation(
-                            id=everyone_else_variation['id'],
-                            key=everyone_else_variation['key'],
-                            featureEnabled=bool(everyone_else_variation.get('featureEnabled', False)),
-                            variables=cast(
-                                Optional[list[entities.Variable]],
-                                everyone_else_variation.get('variables'),
-                            ),
+                        self.variation_key_map[experiment.key][everyone_else_variation.key] = everyone_else_variation
+                        self.variation_id_map[experiment.key][everyone_else_variation.id] = everyone_else_variation
+                        self.variation_id_map_by_experiment_id[experiment.id][everyone_else_variation.id] = (
+                            everyone_else_variation
                         )
-                        self.variation_key_map[experiment.key][var_entity.key] = var_entity
-                        self.variation_id_map[experiment.key][var_entity.id] = var_entity
-                        self.variation_id_map_by_experiment_id[experiment.id][var_entity.id] = var_entity
-                        self.variation_key_map_by_experiment_id[experiment.id][var_entity.key] = var_entity
-                        self.variation_variable_usage_map[var_entity.id] = self._generate_key_map(
-                            var_entity.variables, 'id', entities.Variation.VariableUsage
+                        self.variation_key_map_by_experiment_id[experiment.id][everyone_else_variation.key] = (
+                            everyone_else_variation
+                        )
+                        self.variation_variable_usage_map[everyone_else_variation.id] = self._generate_key_map(
+                            everyone_else_variation.variables, 'id', entities.Variation.VariableUsage
                         )
 
             flag_id = feature.id
@@ -695,7 +698,7 @@ def get_rollout_from_id(self, rollout_id: str) -> Optional[entities.Layer]:
         self.logger.error(f'Rollout with ID "{rollout_id}" is not in datafile.')
         return None
 
-    def _get_everyone_else_variation(self, flag: entities.FeatureFlag) -> Optional[types.VariationDict]:
+    def _get_everyone_else_variation(self, flag: entities.FeatureFlag) -> Optional[entities.Variation]:
         """ Get the "everyone else" variation for a feature flag.
 
         The "everyone else" rule is the last experiment in the flag's rollout,
@@ -705,7 +708,7 @@ def _get_everyone_else_variation(self, flag: entities.FeatureFlag) -> Optional[t
             flag: The feature flag to get the everyone else variation for.
 
         Returns:
-            The "everyone else" variation dict, or None if not available.
+            The "everyone else" Variation entity, or None if not available.
         """
         if not flag.rolloutId:
             return None
@@ -719,7 +722,16 @@ def _get_everyone_else_variation(self, flag: entities.FeatureFlag) -> Optional[t
         if not variations:
             return None
 
-        return variations[0]
+        variation_dict = variations[0]
+        return entities.Variation(
+            id=variation_dict['id'],
+            key=variation_dict['key'],
+            featureEnabled=bool(variation_dict.get('featureEnabled', False)),
+            variables=cast(
+                Optional[list[entities.Variable]],
+                variation_dict.get('variables'),
+            ),
+        )
 
     def get_variable_value_for_variation(
         self, variable: Optional[entities.Variable], variation: Optional[Union[entities.Variation, VariationDict]]