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) }

FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

- Based on https://github.com/oguzbilgic/fpd, which has the following license:
"""

   * 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.");

DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


MIT License
===========

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

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

FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN

MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION

FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN

FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE