contract { callsInPlace(action, InvocationKind.EXACTLY_ONCE) }
    return lock.withLock(action)
  }

  inline fun <T> RealCall.withLock(action: () -> T): T {
    contract { callsInPlace(action, InvocationKind.EXACTLY_ONCE) }
    return lock.withLock(action)
  }

  inline fun <T> Http2Connection.withLock(action: () -> T): T {
    contract { callsInPlace(action, InvocationKind.EXACTLY_ONCE) }

import java.util.Iterator;
import java.util.Map.Entry;
import java.util.SortedMap;

/**
 * Tests representing the contract of {@link SortedMap}. Concrete subclasses of this base class test
 * conformance of concrete {@link SortedMap} subclasses to that contract.
 *
 * @author Jared Levy
 */
// TODO: Use this class to test classes besides ImmutableSortedMap.
@GwtCompatible

   * documentation.
   */
  public void add(Runnable runnable, Executor executor) {
    // 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.");

   * way to obtain a {@code List<ListenableFuture<T>>} from this method is an unchecked (but safe)
   * cast:
   *
   * <pre>
   *   {@code @SuppressWarnings("unchecked") // guaranteed by invokeAll contract}
   *   {@code List<ListenableFuture<T>> futures = (List) executor.invokeAll(tasks);}
   * </pre>
   *
   * @return A list of {@code ListenableFuture} instances representing the tasks, in the same

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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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