*
 * @author Kevin Bourrillion
 * @since 2.0
 */
@GwtCompatible
@FunctionalInterface
public interface Function<F extends @Nullable Object, T extends @Nullable Object>
    extends java.util.function.Function<F, T> {
  @Override
  @ParametricNullness
  T apply(@ParametricNullness F input);

  /**

 * @param data Additional data associated with this request trace, typically containing the actual request
 *             object being processed or any application-specific state information. May be null if no
 *             additional data is needed.
 */
public record RequestTrace(@Nullable String context, @Nullable RequestTrace parent, @Nullable Object data) {

    public static final String CONTEXT_PLUGIN = "plugin";

        // Test case for getResponse method
        Response mockResponse = mock(Response.class); // Mock a response object
        when(mockRequest.getResponse()).thenReturn(mockResponse);

        Response actualResponse = mockRequest.getResponse();

        assertEquals(mockResponse, actualResponse, "Response should match the mocked object.");
        verify(mockRequest, times(1)).getResponse();
    }

    @Test

    //                                                                              ======
    @Override
    public Map<String, Object> toSource() {
        Map<String, Object> sourceMap = new HashMap<>();
        if (createdBy != null) {
            addFieldToSource(sourceMap, "createdBy", createdBy);
        }
        if (createdTime != null) {

    }

    public void test_list_operations_with_metrics() {
        DocList docList = new DocList();

        Map<String, Object> doc1 = new HashMap<>();
        doc1.put("id", "1");
        doc1.put("title", "Test Document 1");

        Map<String, Object> doc2 = new HashMap<>();
        doc2.put("id", "2");
        doc2.put("title", "Test Document 2");

        docList.add(doc1);

    //                                                                              ======
    @Override
    public Map<String, Object> toSource() {
        Map<String, Object> sourceMap = new HashMap<>();
        if (createdBy != null) {
            addFieldToSource(sourceMap, "createdBy", createdBy);
        }
        if (createdTime != null) {

    //                                                                              ======
    @Override
    public Map<String, Object> toSource() {
        Map<String, Object> sourceMap = new HashMap<>();
        if (authRealm != null) {
            addFieldToSource(sourceMap, "authRealm", authRealm);
        }
        if (createdBy != null) {

        .testEquals();
  }

  public void testEquivalentTo() {
    Predicate<@Nullable Object> equalTo1 = Equivalence.equals().equivalentTo("1");
    assertTrue(equalTo1.apply("1"));
    assertFalse(equalTo1.apply("2"));
    assertFalse(equalTo1.apply(null));
    Predicate<@Nullable Object> isNull = Equivalence.equals().equivalentTo(null);
    assertFalse(isNull.apply("1"));
    assertFalse(isNull.apply("2"));

        .testEquals();
  }

  public void testEquivalentTo() {
    Predicate<@Nullable Object> equalTo1 = Equivalence.equals().equivalentTo("1");
    assertTrue(equalTo1.apply("1"));
    assertFalse(equalTo1.apply("2"));
    assertFalse(equalTo1.apply(null));
    Predicate<@Nullable Object> isNull = Equivalence.equals().equivalentTo(null);
    assertFalse(isNull.apply("1"));
    assertFalse(isNull.apply("2"));

   * returns an arbitrary (but consistent) endpoint of the origin edge.
   */
  public final N nodeU() {
    return nodeU;
  }

  /**
   * Returns the node {@link #adjacentNode(Object) adjacent} to {@link #nodeU()} along the origin
   * edge. If this {@link EndpointPair} {@link #isOrdered()}, this is equal to {@link #target()}.
   */
  public final N nodeV() {
    return nodeV;
  }

  /**