public class CollectionRetainAllTester<E> extends AbstractCollectionTester<E> {

  /** A collection of elements to retain, along with a description for use in failure messages. */
  private final class Target {
    private final Collection<E> toRetain;
    private final String description;

    private Target(Collection<E> toRetain, String description) {
      this.toRetain = toRetain;
      this.description = description;
    }

- **Reduced memory allocation** in collection operations and bean copying
- **Improved reflection performance** with cached descriptors and optimized field access
- **Enhanced collection operations** with Java 21 sequenced collections support
- **Better concurrent performance** using modern concurrent collection implementations

## 🔧 Configuration

### Logging Configuration

    }

    @CanIgnoreReturnValue
    @Override
    public Builder<E> addAll(Iterable<? extends E> elements) {
      if (elements instanceof Collection) {
        Collection<?> collection = (Collection<?>) elements;
        contents.ensureCapacity(contents.size() + collection.size());
      }
      super.addAll(elements);
      return this;
    }

    @CanIgnoreReturnValue
    @Override

     * If the value is a Collection containing Entity objects, each Entity will be converted to a Map.
     * For other types of values, they are registered directly.
     *
     * @param data the RenderData object to register the value in
     * @param key the key to associate with the value
     * @param value the value to register; can be null, Entity, Collection, or any other object
     */

    throw new UnsupportedOperationException();
  }

  @Override
  public final boolean addAll(Collection<? extends E> newElements) {
    throw new UnsupportedOperationException();
  }

  @Override
  public final boolean removeAll(Collection<?> oldElements) {
    throw new UnsupportedOperationException();
  }

  @Override

  @CollectionFeature.Require(absent = KNOWN_ORDER)
  public void testSpliteratorUnknownOrder() {
    SpliteratorTester.of(collection::spliterator).expect(getSampleElements());
  }

  @CollectionFeature.Require(KNOWN_ORDER)
  public void testSpliteratorKnownOrder() {
    SpliteratorTester.of(collection::spliterator).expect(getOrderedElements()).inOrder();
  }

  @CollectionFeature.Require(ALLOWS_NULL_VALUES)

        throwIfUnchecked(e);
        throw new RuntimeException(e);
      }
    };
  }

  /**
   * Wraps a collection of tasks.
   *
   * @throws NullPointerException if any element of {@code tasks} is null
   */
  private <T extends @Nullable Object> ImmutableList<Callable<T>> wrapTasks(
      Collection<? extends Callable<T>> tasks) {
    ImmutableList.Builder<Callable<T>> builder = ImmutableList.builder();

                public int size() {
                    return 0;
                }
            };
        }
    };

    static <E1, E2 extends E1> List<E1> copy(Collection<E2> collection) {
        return collection == null ? List.of() : List.copyOf(collection);
    }

    static <K, V> Map<K, V> copy(Map<K, V> map) {
        if (map == null) {
            return emptyMap();

   * Returns an array containing all of the elements in the specified collection; the runtime type
   * of the returned array is that of the specified array. If the collection fits in the specified
   * array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the
   * specified array and the size of the specified collection.
   *
   * <p>If the collection fits in the specified array with room to spare (i.e., the array has more

      Collection<V> collection) {
    if (collection instanceof SortedSet) {
      return Collections.unmodifiableSortedSet((SortedSet<V>) collection);
    } else if (collection instanceof Set) {
      return Collections.unmodifiableSet((Set<V>) collection);
    } else if (collection instanceof List) {
      return Collections.unmodifiableList((List<V>) collection);
    }