Iterator<? extends T> a,
      Iterator<? extends T> b,
      Iterator<? extends T> c,
      Iterator<? extends T> d) {
    checkNotNull(a);
    checkNotNull(b);
    checkNotNull(c);
    checkNotNull(d);
    return concat(consumingForArray(a, b, c, d));
  }

  /**
   * Combines multiple iterators into a single iterator. The returned iterator iterates across the

    }
  }

  /*
   * Preconditions.checkNotNull is *intended* for performing eager null checks on parameters that a
   * nullness checker can already "prove" are non-null. That means that the first parameter to
   * checkNotNull *should* be annotated to require it to be non-null.
   *

   */
  public static <T extends @Nullable Object> Iterable<T> filter(
      final Iterable<T> unfiltered, final Predicate<? super T> retainIfTrue) {
    checkNotNull(unfiltered);
    checkNotNull(retainIfTrue);
    return new FluentIterable<T>() {
      @Override
      public Iterator<T> iterator() {
        return Iterators.filter(unfiltered.iterator(), retainIfTrue);
      }
    };

    }

    final void addDelayedShutdownHook(
        final ExecutorService service, final long terminationTimeout, final TimeUnit timeUnit) {
      checkNotNull(service);
      checkNotNull(timeUnit);
      addShutdownHook(
          MoreExecutors.newThread(
              "DelayedShutdownHook-for-" + service,
              new Runnable() {
                @Override

    TypeVariableImpl(D genericDeclaration, String name, Type[] bounds) {
      disallowPrimitiveType(bounds, "bound for type variable");
      this.genericDeclaration = checkNotNull(genericDeclaration);
      this.name = checkNotNull(name);
      this.bounds = ImmutableList.copyOf(bounds);
    }

    public Type[] getBounds() {
      return toArray(bounds);
    }

    public D getGenericDeclaration() {

   */
  public static <K extends @Nullable Object, V extends @Nullable Object>
      SortedMapDifference<K, V> difference(
          SortedMap<K, ? extends V> left, Map<? extends K, ? extends V> right) {
    checkNotNull(left);
    checkNotNull(right);
    Comparator<? super K> comparator = orNaturalOrder(left.comparator());
    SortedMap<K, V> onlyOnLeft = Maps.newTreeMap(comparator);
    SortedMap<K, V> onlyOnRight = Maps.newTreeMap(comparator);

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

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.CollectPreconditions.checkNonnegative;

import com.google.common.annotations.GwtCompatible;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;

    // Fail fast on a null. We throw NPE here because the contract of Executor states that it throws
    // NPE on null listener, so we propagate that contract up into the add method as well.
    checkNotNull(runnable, "Runnable was null.");
    checkNotNull(executor, "Executor was null.");

    // Lock while we check state. We must maintain the lock while adding the new pair so that

  final Predicate<? super Entry<K, V>> predicate;

  FilteredEntryMultimap(Multimap<K, V> unfiltered, Predicate<? super Entry<K, V>> predicate) {
    this.unfiltered = checkNotNull(unfiltered);
    this.predicate = checkNotNull(predicate);
  }

  @Override
  public Multimap<K, V> unfiltered() {
    return unfiltered;
  }

  @Override
  public Predicate<? super Entry<K, V>> entryPredicate() {

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

package com.google.common.collect.testing;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.testing.Helpers.assertEqualIgnoringOrder;
import static com.google.common.collect.testing.Helpers.assertEqualInOrder;
import static com.google.common.collect.testing.Platform.format;