synchronized (messagesLock) {
            if (messages == null) {
                this.messages = null;
            } else if (messages instanceof CopyOnWriteArrayList) {
                this.messages = messages;
            } else {
                this.messages = new CopyOnWriteArrayList<>(messages);
            }
        }
    }

    /**
     * Adds a message to this session and updates the last accessed timestamp.

     * Creates and returns a new instance of {@link CopyOnWriteArrayList}.
     *
     * @param <E> the element type of {@link CopyOnWriteArrayList}
     * @return a new instance of {@link CopyOnWriteArrayList}
     * @see CopyOnWriteArrayList#CopyOnWriteArrayList()
     */
    public static <E> CopyOnWriteArrayList<E> newCopyOnWriteArrayList() {
        return new CopyOnWriteArrayList<>();
    }

    /**

  public static <E extends @Nullable Object> CopyOnWriteArrayList<E> newCopyOnWriteArrayList() {
    return new CopyOnWriteArrayList<>();
  }

  /**
   * Creates a {@code CopyOnWriteArrayList} instance containing the given elements.
   *
   * @param elements the elements that the list should contain, in order
   * @return a new {@code CopyOnWriteArrayList} containing those elements

  public static <E extends @Nullable Object> CopyOnWriteArrayList<E> newCopyOnWriteArrayList() {
    return new CopyOnWriteArrayList<>();
  }

  /**
   * Creates a {@code CopyOnWriteArrayList} instance containing the given elements.
   *
   * @param elements the elements that the list should contain, in order
   * @return a new {@code CopyOnWriteArrayList} containing those elements

      Collection<Integer> initialContents, Iterable<ListFrobber> actionsToPerformConcurrently) {
    InvocationHandler invocationHandler =
        new InvocationHandler() {
          final CopyOnWriteArrayList<Integer> delegate =
              new CopyOnWriteArrayList<>(initialContents);

          final Method getAllStatesMethod =
              getOnlyElement(asList(ConcurrentlyMutatedList.class.getDeclaredMethods()));

 * Tests the improvements made to thread safety using CopyOnWriteArrayList.
 */
public class RankFusionProcessorConcurrencyTest extends UnitFessTestCase {

    private static final String ID_FIELD = "_id";

    /**
     * Test concurrent registration of searchers from multiple threads.
     * Verifies that CopyOnWriteArrayList handles concurrent modifications safely.
     */
    @Test

import com.google.common.collect.testing.features.ListFeature;
import com.google.common.testing.SerializableTester;
import java.lang.reflect.Method;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@code subList()} operations on a list. Can't be invoked
 * directly; please see {@link com.google.common.collect.testing.ListTestSuiteBuilder}.
 *

import com.google.common.collect.testing.features.ListFeature;
import com.google.common.testing.SerializableTester;
import java.lang.reflect.Method;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@code subList()} operations on a list. Can't be invoked
 * directly; please see {@link com.google.common.collect.testing.ListTestSuiteBuilder}.
 *

            new TestStringListGenerator() {
              @Override
              public List<String> create(String[] elements) {
                return new CopyOnWriteArrayList<>(MinimalCollection.of(elements));
              }
            })
        .named("CopyOnWriteArrayList")
        .withFeatures(
            ListFeature.SUPPORTS_ADD_WITH_INDEX,
            ListFeature.SUPPORTS_REMOVE_WITH_INDEX,

     */
    @Test
    public void testConcurrentListenerInvocation() throws Exception {
        // This test verifies CopyOnWriteArrayList allows safe iteration
        assertTrue(fesenClient.onConnectListenerList instanceof java.util.concurrent.CopyOnWriteArrayList);
    }

    /**
     * Test: Retry logic correctly enforces maxRetryCount