underlying.put("b", "");

    Map<@Nullable String, Boolean> map =
        transformValues(
            underlying,
            new Function<@Nullable String, Boolean>() {
              @Override
              public Boolean apply(@Nullable String from) {
                return from == null;
              }
            });
    Map<String, Boolean> expected = ImmutableMap.of("a", true, "b", false);

        }

        @Override
        public boolean removeAll(Collection<?> c) {
          return removeEntriesIf(Maps.<K>keyPredicateOnEntries(in(c)));
        }

        @Override
        public boolean retainAll(Collection<?> c) {
          return removeEntriesIf(Maps.<K>keyPredicateOnEntries(not(in(c))));
        }

        @Override
        public boolean remove(@CheckForNull Object o) {

        }

        @Override
        public boolean removeAll(Collection<?> c) {
          return removeEntriesIf(Maps.<K>keyPredicateOnEntries(in(c)));
        }

        @Override
        public boolean retainAll(Collection<?> c) {
          return removeEntriesIf(Maps.<K>keyPredicateOnEntries(not(in(c))));
        }

        @Override
        public boolean remove(@CheckForNull Object o) {

    underlying.put("b", "");

    Map<String, Boolean> map =
        transformValues(
            underlying,
            new Function<@Nullable String, Boolean>() {
              @Override
              public Boolean apply(@Nullable String from) {
                return from == null;
              }
            });
    Map<String, Boolean> expected = ImmutableMap.of("a", true, "b", false);

    }
  }

  private abstract static class MapTests extends MapInterfaceTest<String, Integer> {

    MapTests(
        boolean allowsNullValues,
        boolean supportsPut,
        boolean supportsRemove,
        boolean supportsClear,
        boolean supportsIteratorRemove) {
      super(
          false,
          allowsNullValues,
          supportsPut,
          supportsRemove,

    }
  }

  private abstract static class MapTests extends MapInterfaceTest<String, Integer> {

    MapTests(
        boolean allowsNullValues,
        boolean supportsPut,
        boolean supportsRemove,
        boolean supportsClear,
        boolean supportsIteratorRemove) {
      super(
          false,
          allowsNullValues,
          supportsPut,
          supportsRemove,

      }
    }

    @Override
    public boolean contains(@CheckForNull Object o) {
      synchronized (mutex) {
        return delegate().contains(o);
      }
    }

    @Override
    public boolean containsAll(Collection<?> c) {
      synchronized (mutex) {
        return delegate().containsAll(c);
      }
    }

    @Override
    public boolean isEmpty() {
      synchronized (mutex) {

      }
    }

    @Override
    public boolean contains(@CheckForNull Object o) {
      synchronized (mutex) {
        return delegate().contains(o);
      }
    }

    @Override
    public boolean containsAll(Collection<?> c) {
      synchronized (mutex) {
        return delegate().containsAll(c);
      }
    }

    @Override
    public boolean isEmpty() {
      synchronized (mutex) {

   * wasn't going to be any actual work to do anyway
   */

  @Override
  public boolean addAll(Collection<? extends E> elementsToAdd) {
    throw up();
  }

  @Override
  public boolean removeAll(Collection<?> elementsToRemove) {
    throw up();
  }

  @Override
  public boolean retainAll(Collection<?> elementsToRetain) {
    throw up();
  }

  @Override

    public String toString() {
      return "IncompatibleKeyType";
    }
  }

  protected final boolean supportsPut;
  protected final boolean supportsRemove;
  protected final boolean supportsClear;
  protected final boolean allowsNullKeys;
  protected final boolean allowsNullValues;
  protected final boolean supportsIteratorRemove;

  /**
   * Creates a new, empty instance of the class under test.
   *