// Split out all the specified sizes.
    Set<Feature<?>> sizesToTest = Helpers.copyToSet(CollectionSize.values());
    sizesToTest.retainAll(features);
    features.removeAll(sizesToTest);

    addImpliedFeatures(sizesToTest);
    sizesToTest.retainAll(asList(CollectionSize.ZERO, CollectionSize.ONE, CollectionSize.SEVERAL));

    logger.fine("   Sizes: " + formatFeatureSet(sizesToTest));

      assertThat(keys.remove(6)).isFalse();
      assertThat(keys.remove(-6)).isFalse();
      assertThat(keys.removeAll(asList(null, 0, 15, 1500))).isFalse();
      assertThat(keys.retainAll(asList(null, 0, 15, 1500))).isFalse();
      checkEmpty(keys);
      checkEmpty(cache);
    }
  }

  public void testKeySet_remove() {
    for (LoadingCache<Object, Object> cache : caches()) {

      assertThat(keys.remove(6)).isFalse();
      assertThat(keys.remove(-6)).isFalse();
      assertThat(keys.removeAll(asList(null, 0, 15, 1500))).isFalse();
      assertThat(keys.retainAll(asList(null, 0, 15, 1500))).isFalse();
      checkEmpty(keys);
      checkEmpty(cache);
    }
  }

  public void testKeySet_remove() {
    for (LoadingCache<Object, Object> cache : caches()) {

        @Override
        public boolean removeAll(Collection<?> c) {
          return delegate.keySet().removeAll(c);
        }

        @Override
        public boolean retainAll(Collection<?> c) {
          return delegate.keySet().retainAll(c);
        }
      };
    }

    @Override
    public Collection<V> values() {
      return new ForwardingCollection<V>() {
        @Override

    }
  }

  @Override
  public void testEntrySetRetainAllNullFromEmpty() {
    try {
      super.testEntrySetRetainAllNullFromEmpty();
    } catch (RuntimeException tolerated) {
      // GWT's TreeMap.entrySet().retainAll(null) doesn't throws NPE.
    }
  }

  @Override
  public void testKeySetRemoveAllNullFromEmpty() {
    try {
      super.testKeySetRemoveAllNullFromEmpty();
    } catch (RuntimeException tolerated) {

  }

  @CollectionSize.Require(ONE)
  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testEntrySet_retainAllPresent() {
    assertFalse(
        "multiset.entrySet.retainAll(presentEntry) returned false",
        getMultiset().entrySet().retainAll(singleton(Multisets.immutableEntry(e0(), 1))));
    assertTrue(
        "multiset doesn't contains element after retaining its entry",
        getMultiset().contains(e0()));
  }

import java.lang.reflect.Method;
import java.util.List;
import org.junit.Ignore;

/**
 * Tests for {@code Multiset#remove}, {@code Multiset.removeAll}, and {@code Multiset.retainAll} not
 * already covered by the corresponding Collection testers.
 *
 * @author Jared Levy
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")

import java.lang.reflect.Method;
import java.util.List;
import org.junit.Ignore;

/**
 * Tests for {@code Multiset#remove}, {@code Multiset.removeAll}, and {@code Multiset.retainAll} not
 * already covered by the corresponding Collection testers.
 *
 * @author Jared Levy
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")

      boolean didRemove = entrySet.retainAll(entriesToRetain);
      assertEquals(shouldRemove, didRemove);
      assertEquals(entriesToRetain.size(), map.size());
      for (Entry<K, V> entry : entriesToRetain) {
        assertTrue(entrySet.contains(entry));
      }
    } else {
      assertThrows(UnsupportedOperationException.class, () -> entrySet.retainAll(entriesToRetain));
    }
    assertInvariants(map);

  }

  @CollectionSize.Require(ONE)
  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testEntrySet_retainAllPresent() {
    assertFalse(
        "multiset.entrySet.retainAll(presentEntry) returned false",
        getMultiset().entrySet().retainAll(singleton(Multisets.immutableEntry(e0(), 1))));
    assertTrue(
        "multiset doesn't contains element after retaining its entry",
        getMultiset().contains(e0()));
  }