* {@code get(null)}, {@code keySet().contains(null)} or {@code remove(null)}.
   */
  ALLOWS_NULL_KEY_QUERIES,
  ALLOWS_NULL_KEYS(ALLOWS_NULL_KEY_QUERIES),
  /**
   * The map does not throw {@code NullPointerException} on calls such as {@code
   * containsValue(null)}, {@code values().contains(null)} or {@code values().remove(null)}.
   */
  ALLOWS_NULL_VALUE_QUERIES,
  ALLOWS_NULL_VALUES(ALLOWS_NULL_VALUE_QUERIES),

  }

  public void testRemove() {
    TestMap map = new TestMap();
    map.put("foo", 1);
    assertFalse(map.remove("foo", 2));
    assertFalse(map.remove("bar", 1));
    assertEquals(Integer.valueOf(1), map.get("foo"));
    assertTrue(map.remove("foo", 1));
    assertTrue(map.isEmpty());
  }

  public void testReplace() {
    TestMap map = new TestMap();
    map.put("foo", 1);

    }

    public void mymodifyProperty(String propertyName) {
        registerModifiedProperty(propertyName);
    }

    public void mymodifyPropertyCancel(String propertyName) {
        __modifiedProperties.remove(propertyName);
    }

    public void clearModifiedInfo() {
        __modifiedProperties.clear();
    }

    public boolean hasModification() {
        return !__modifiedProperties.isEmpty();
    }

    }

    public void mymodifyProperty(String propertyName) {
        registerModifiedProperty(propertyName);
    }

    public void mymodifyPropertyCancel(String propertyName) {
        __modifiedProperties.remove(propertyName);
    }

    public void clearModifiedInfo() {
        __modifiedProperties.clear();
    }

    public boolean hasModification() {
        return !__modifiedProperties.isEmpty();
    }

    Set<Feature<?>> inverseFeatures = new HashSet<>(mapFeatures);

    boolean nullKeys = inverseFeatures.remove(MapFeature.ALLOWS_NULL_KEYS);
    boolean nullValues = inverseFeatures.remove(MapFeature.ALLOWS_NULL_VALUES);

    if (nullKeys) {
      inverseFeatures.add(MapFeature.ALLOWS_NULL_VALUES);
    }
    if (nullValues) {

distribution or licensing of Covered Software under this License.
Notwithstanding Section 2.1(b) above, no patent license is granted by a
Contributor:

(a) for any code that a Contributor has removed from Covered Software;
    or

(b) for infringements caused by: (i) Your and any other third party's
    modifications of Covered Software, or (ii) the combination of its

		FreeVersion: fi.TierFreeVersion(),
		Tier:        fi.TransitionTier,
	}

	// etag/md5Sum has already been extracted. We need to
	// remove to avoid it from appearing as part of
	// response headers. e.g, X-Minio-* or X-Amz-*.
	// Tags have also been extracted, we remove that as well.
	objInfo.UserDefined = cleanMetadata(fi.Metadata)

	// All the parts per object.
	objInfo.Parts = fi.Parts

        return delegate().iterator();
      }

      @Override
      public int size() {
        return delegate().size();
      }

      @Override
      public boolean remove(Object o) {
        return delegate().remove(o);
      }

      @Override
      public void clear() {
        delegate().clear();
      }
    };
  }

  @Override
  public @Nullable Entry<K, V> firstEntry() {

    throw new UnsupportedOperationException();
  }

  @CanIgnoreReturnValue
  @Override
  public final boolean remove(@Nullable Object element) {
    return remove(element, 1) > 0;
  }

  @CanIgnoreReturnValue
  @Override
  public int remove(@Nullable Object element, int occurrences) {
    throw new UnsupportedOperationException();
  }

  @CanIgnoreReturnValue
  @Override

        if (cycle != null) {
            // remove edge which introduced cycle
            removeEdge(from, to);
            throw new CycleDetectedException(
                    "Edge between '" + from.label + "' and '" + to.label + "' introduces to cycle in the graph", cycle);
        }
    }

    void removeEdge(Vertex from, Vertex to) {
        from.children.remove(to);
        to.parents.remove(from);
    }