refactor: Move internal utilities from API to SDK module

Moved implementation-specific internal utilities from the API module to the SDK
module to create a cleaner API contract:

## Moved Classes
- **AutoCloseableLock** & **AutoCloseableReentrantReadWriteLock**: Thread-safe locking utilities used by SDK implementation
- **ObjectUtils**: Collection merging and null-handling utilities for SDK operations
- **TriConsumer**: Functional interface used by SDK event handling system

## Kept in API
- **ExcludeFromGeneratedCoverageReport**: Testing annotation that API implementations may use

## Benefits
- **Cleaner API**: API module now contains only essential contracts and interfaces
- **Better Separation**: Implementation utilities properly isolated in SDK module
- **Reduced Dependencies**: API consumers don't get unnecessary internal utilities
- **Maintained Functionality**: All SDK features continue to work with updated imports

Both API and SDK modules compile and test successfully after the refactoring.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: aepfli

openfeature-sdk/src/main/java/dev/openfeature/sdk/DefaultOpenFeatureAPI.java

@@ -11,8 +11,8 @@
 import dev.openfeature.api.ProviderEventDetails;
 import dev.openfeature.api.ProviderState;
 import dev.openfeature.api.exceptions.OpenFeatureError;
-import dev.openfeature.api.internal.AutoCloseableLock;
-import dev.openfeature.api.internal.AutoCloseableReentrantReadWriteLock;
+import dev.openfeature.sdk.internal.AutoCloseableLock;
+import dev.openfeature.sdk.internal.AutoCloseableReentrantReadWriteLock;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;

openfeature-sdk/src/main/java/dev/openfeature/sdk/EventProvider.java

@@ -4,7 +4,7 @@
 import dev.openfeature.api.FeatureProvider;
 import dev.openfeature.api.ProviderEvent;
 import dev.openfeature.api.ProviderEventDetails;
-import dev.openfeature.api.internal.TriConsumer;
+import dev.openfeature.sdk.internal.TriConsumer;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;

openfeature-sdk/src/main/java/dev/openfeature/sdk/OpenFeatureClient.java

@@ -24,7 +24,7 @@
 import dev.openfeature.api.exceptions.GeneralError;
 import dev.openfeature.api.exceptions.OpenFeatureError;
 import dev.openfeature.api.exceptions.ProviderNotReadyError;
-import dev.openfeature.api.internal.ObjectUtils;
+import dev.openfeature.sdk.internal.ObjectUtils;
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 import java.util.ArrayList;
 import java.util.Arrays;

openfeature-api/src/main/java/dev/openfeature/api/internal/AutoCloseableLock.java renamed to openfeature-sdk/src/main/java/dev/openfeature/sdk/internal/AutoCloseableLock.java

@@ -1,4 +1,4 @@
-package dev.openfeature.api.internal;
+package dev.openfeature.sdk.internal;
 
 @SuppressWarnings("checkstyle:MissingJavadocType")
 public interface AutoCloseableLock extends AutoCloseable {

openfeature-api/src/main/java/dev/openfeature/api/internal/AutoCloseableReentrantReadWriteLock.java renamed to openfeature-sdk/src/main/java/dev/openfeature/sdk/internal/AutoCloseableReentrantReadWriteLock.java

@@ -1,4 +1,4 @@
-package dev.openfeature.api.internal;
+package dev.openfeature.sdk.internal;
 
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 

openfeature-api/src/main/java/dev/openfeature/api/internal/ObjectUtils.java renamed to openfeature-sdk/src/main/java/dev/openfeature/sdk/internal/ObjectUtils.java

@@ -1,4 +1,4 @@
-package dev.openfeature.api.internal;
+package dev.openfeature.sdk.internal;
 
 import java.util.ArrayList;
 import java.util.Collection;

openfeature-api/src/main/java/dev/openfeature/api/internal/TriConsumer.java renamed to openfeature-sdk/src/main/java/dev/openfeature/sdk/internal/TriConsumer.java

@@ -1,4 +1,4 @@
-package dev.openfeature.api.internal;
+package dev.openfeature.sdk.internal;
 
 import java.util.Objects;