Method execute

api/src/test/java/io/grpc/ContextTest.java:365–369

(Runnable runnable)

      final Error err = new Error();
      base.addListener(cancellationListener, new Executor() {
        @Override
        public void execute(Runnable runnable) {
          observed1.set(runnable);
          throw err;
        }
      });
      assertNull(observed1.get());
      assertNull(loggedThrowable.get());