return compareResult == 0;
      } catch (ClassCastException wastNotComparableToOurType) {
        return false;
      }
    }
    return false;
  }

  // Prevent "missing hashCode" warning by explicitly forcing subclasses implement it
  @Override
  public abstract int hashCode();

  /*
   * The implementation neither produces nor consumes any non-null instance of type C, so

 * references. It would not make sense to consider {@code null} and a non-null reference to be
 * "different representations of the same information", since one is distinguishable from
 * <i>missing</i> information and the other is not. The {@link #convert} method handles this null
 * behavior for all converters; implementations of {@link #doForward} and {@link #doBackward} are

    putEdge(N1, N2);

    assertThat(graphAsMutableGraph.putEdge(N2, N1)).isFalse();
  }

  /**
   * Tests that the method {@code putEdge} will silently add the missing nodes to the graph, then
   * add the edge connecting them. We are not using the proxy methods here as we want to test {@code
   * putEdge} when the end-points are not elements of the graph.
   */
  @Test

        // all, the definition of subscribers on a particular class is totally static
        throw new IllegalArgumentException(
            "missing event subscriber for an annotated method. Is " + listener + " registered?");
      }

      // don't try to remove the set if it's empty; that can't be done safely without a lock

    }
  }

  public static class ImmutableSetWithBadHashesGenerator extends TestCollidingSetGenerator
      // Work around a GWT compiler bug.  Not explicitly listing this will
      // cause the createArray() method missing in the generated javascript.
      // TODO: Remove this once the GWT bug is fixed.
      implements TestCollectionGenerator<Object> {
    @Override
    public Set<Object> create(Object... elements) {

    assertThat(e).hasMessageThat().contains(ERROR_SELF_LOOP);
  }

  /**
   * This test checks an implementation dependent feature. It tests that the method {@code addEdge}
   * will silently add the missing nodes to the graph, then add the edge connecting them. We are not
   * using the proxy methods here as we want to test {@code addEdge} when the end-points are not
   * elements of the graph.
   */
  @Test

    assertEquals(multimap.hashCode(), unmodifiable.hashCode());
    assertEquals(multimap, unmodifiable);

    assertThat(unmodifiable.asMap().get("bar")).containsExactly(5, -1);
    assertNull(unmodifiable.asMap().get("missing"));

    assertFalse(unmodifiable.entries() instanceof Serializable);
  }

  /** Prepares the multimap for unmodifiable tests, returning an unmodifiable view of the map. */

    assertThat(e).hasMessageThat().contains(ERROR_SELF_LOOP);
  }

  /**
   * This test checks an implementation dependent feature. It tests that the method {@code addEdge}
   * will silently add the missing nodes to the graph, then add the edge connecting them. We are not
   * using the proxy methods here as we want to test {@code addEdge} when the end-points are not
   * elements of the graph.
   */
  @Test

            IllegalArgumentException.class, () -> graph.removeEdge(EndpointPair.ordered(2, 1)));
    assertThat(e).hasMessageThat().contains(ENDPOINTS_MISMATCH);
  }

  @Test
  public void edgeValue_missing() {
    graph = ValueGraphBuilder.directed().build();

    assertThat(graph.edgeValueOrDefault(1, 2, DEFAULT)).isEqualTo(DEFAULT);
    assertThat(graph.edgeValueOrDefault(2, 1, DEFAULT)).isEqualTo(DEFAULT);

    assertThat(e).hasMessageThat().contains(ERROR_SELF_LOOP);
  }

  /**
   * This test checks an implementation dependent feature. It tests that the method {@code addEdge}
   * will silently add the missing nodes to the graph, then add the edge connecting them. We are not
   * using the proxy methods here as we want to test {@code addEdge} when the end-points are not
   * elements of the graph.
   */
  @Test