* limitations under the License.
 */

package com.google.common.collect;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.Multisets.UnmodifiableMultiset;
import com.google.errorprone.annotations.concurrent.LazyInit;
import java.util.Comparator;
import java.util.NavigableSet;
import javax.annotation.CheckForNull;

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import com.google.common.collect.Multisets.UnmodifiableMultiset;
import java.util.Collections;
import java.util.Comparator;
import java.util.SortedSet;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**

    Multiset<String> unmod = Multisets.unmodifiableMultiset(mod);
    assertNotSame(mod, unmod);
    assertSame(unmod, Multisets.unmodifiableMultiset(unmod));
    ImmutableMultiset<String> immutable = ImmutableMultiset.of("a", "a", "b", "a");
    assertSame(immutable, Multisets.unmodifiableMultiset(immutable));
    assertSame(immutable, Multisets.unmodifiableMultiset((Multiset<String>) immutable));
  }

                CollectionSize.ANY,
                CollectionFeature.KNOWN_ORDER,
                CollectionFeature.SERIALIZABLE,
                CollectionFeature.ALLOWS_NULL_QUERIES)
            .named("Multisets.unmodifiableMultiset[LinkedHashMultiset]")
            .createTestSuite());

    suite.addTest(
        SortedMultisetTestSuiteBuilder.using(unmodifiableSortedMultisetGenerator())
            .withFeatures(

                CollectionSize.ANY,
                CollectionFeature.KNOWN_ORDER,
                CollectionFeature.SERIALIZABLE,
                CollectionFeature.ALLOWS_NULL_QUERIES)
            .named("Multisets.unmodifiableMultiset[LinkedHashMultiset]")
            .createTestSuite());

    suite.addTest(
        SortedMultisetTestSuiteBuilder.using(unmodifiableSortedMultisetGenerator())
            .withFeatures(

    Multiset<String> unmod = Multisets.unmodifiableMultiset(mod);
    assertNotSame(mod, unmod);
    assertSame(unmod, Multisets.unmodifiableMultiset(unmod));
    ImmutableMultiset<String> immutable = ImmutableMultiset.of("a", "a", "b", "a");
    assertSame(immutable, Multisets.unmodifiableMultiset(immutable));
    assertSame(immutable, Multisets.unmodifiableMultiset((Multiset<String>) immutable));
  }

      Multiset<? extends E> multiset) {
    if (multiset instanceof UnmodifiableMultiset || multiset instanceof ImmutableMultiset) {
      @SuppressWarnings("unchecked") // Since it's unmodifiable, the covariant cast is safe
      Multiset<E> result = (Multiset<E>) multiset;
      return result;
    }
    return new UnmodifiableMultiset<>(checkNotNull(multiset));
  }

    }

    @Override
    public Multiset<K> keys() {
      Multiset<K> result = keys;
      if (result == null) {
        keys = result = Multisets.unmodifiableMultiset(delegate.keys());
      }
      return result;
    }

    @Override
    public Set<K> keySet() {
      Set<K> result = keySet;
      if (result == null) {