assertThat(segment.get(key, hash)).isEqualTo(value);
    assertTrue(segment.containsKey(key, hash));
    assertTrue(segment.containsValue(value));
    assertFalse(segment.containsValue(nullValue));

    // hash collision
    InternalEntry<Object, Object, ?> dummyEntry =
        segment.newEntryForTesting(new Object(), hash, entry);
    Object dummyValue = new Object();
    WeakValueReference<Object, Object, ?> dummyValueRef =

    assertThat(segment.get(key, hash)).isEqualTo(value);
    assertTrue(segment.containsKey(key, hash));
    assertTrue(segment.containsValue(value));
    assertFalse(segment.containsValue(nullValue));

    // hash collision
    InternalEntry<Object, Object, ?> dummyEntry =
        segment.newEntryForTesting(new Object(), hash, entry);
    Object dummyValue = new Object();
    WeakValueReference<Object, Object, ?> dummyValueRef =

        // probably intended. So no point in using an equal-but-different factory argument.
        // We check twice to avoid confusion caused by accidental hash collision.
        equalArgs.set(i, shouldBeEqualArg);
      }
    }
    return equalArgs;
  }

  private static boolean hashCodeInsensitiveToArgReference(

      int leftCode = identityHashCode(left);
      int rightCode = identityHashCode(right);
      if (leftCode != rightCode) {
        return leftCode < rightCode ? -1 : 1;
      }

      // identityHashCode collision (rare, but not as rare as you'd think)
      int result = getUid(left).compareTo(getUid(right));
      if (result == 0) {
        throw new AssertionError(); // extremely, extremely unlikely.
      }

    assertThat(segment.containsKey(key, hash)).isTrue();
    assertThat(segment.containsValue(value)).isTrue();
    assertThat(segment.containsValue(nullValue)).isFalse();

    // hash collision
    DummyEntry<Object, Object> dummy = DummyEntry.create(new Object(), hash, entry);
    Object dummyValue = new Object();
    ValueReference<Object, Object> dummyValueRef = map.newValueReference(dummy, dummyValue, 1);

    assertThat(segment.containsKey(key, hash)).isTrue();
    assertThat(segment.containsValue(value)).isTrue();
    assertThat(segment.containsValue(nullValue)).isFalse();

    // hash collision
    DummyEntry<Object, Object> dummy = DummyEntry.create(new Object(), hash, entry);
    Object dummyValue = new Object();
    ValueReference<Object, Object> dummyValueRef = map.newValueReference(dummy, dummyValue, 1);

      int leftCode = identityHashCode(left);
      int rightCode = identityHashCode(right);
      if (leftCode != rightCode) {
        return leftCode < rightCode ? -1 : 1;
      }

      // identityHashCode collision (rare, but not as rare as you'd think)
      int result = getUid(left).compareTo(getUid(right));
      if (result == 0) {
        throw new AssertionError(); // extremely, extremely unlikely.
      }

*   Add support for the shrinkage-type L2 to FtrlOptimizer in addition to the
    online L2 it already supports.
*   Fix negative variance in moments calculation.
*   Expand UniqueOp Benchmark Tests to cover more collision cases.
*   Improves stability of GCS filesystem on Mac.
*   Add time estimation to HloCostAnalysis.
*   Fixed the bug in Estimator that params in constructor was not a deepcopy of

  // (1) 00 01 02 03 04 05 06 07 80
  // (2) 00 01 02 03 04 05 06 07 81
  // (3) 00 01 02 03 04 05 06 07 ff (or anything in between)
  // A fault implementation will generate collisions for these inputs.
  public void testCollisionsDueToIncorrectSignExtension() {
    byte[] col1 = new byte[] {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, (byte) 0x80};

  // (1) 00 01 02 03 04 05 06 07 80
  // (2) 00 01 02 03 04 05 06 07 81
  // (3) 00 01 02 03 04 05 06 07 ff (or anything in between)
  // A fault implementation will generate collisions for these inputs.
  public void testCollisionsDueToIncorrectSignExtension() {
    byte[] col1 = new byte[] {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, (byte) 0x80};