If we're building with JDK8, then clearly we're sticking to
                   JDK8 APIs. However, I assume (but did not confirm) that we'd
                   have the same issue with our -android builds, which need
                   animal-sniffer so that they can check that we're sticking to
                   JDK6-like APIs.

                   So instead, we use javac9, which doesn't lead to this error.

   * visited twice if there is an edge connecting them. To avoid returning duplicate {@link
   * EndpointPair}s, we keep track of the nodes that we have visited. When processing endpoint
   * pairs, we skip if the "other node" is in the visited set, as shown below:
   *
   * <pre>
   * Nodes = {N1, N2, N3, N4}
   *    N2           __
   *   /  \         |  |

// scanners.
func (s *Scanner) Scan() bool {
	if s.done {
		return false
	}
	s.scanCalled = true
	// Loop until we have a token.
	for {
		// See if we can get a token with what we already have.
		// If we've run out of data but have an error, give the split function
		// a chance to recover any remaining, possibly empty token.
		if s.end > s.start || s.err != nil {

         */
        return 0;
    }


    /*
     * We overload this method from ServerMessageBlock because
     * we want writeAndXWireFormat to write the parameterWords
     * and bytes. This is so we can write batched smbs because
     * all but the first smb of the chaain do not have a header
     * and therefore we do not want to writeHeaderWireFormat. We
     * just recursivly call writeAndXWireFormat.
     */

      if (!firstTimeSeen) {
        /*
         * We've seen this, so we've seen its causes, too. No need to re-add them. (There's one case
         * where this isn't true, but we ignore it: If we record an exception, then someone calls
         * initCause() on it, and then we examine it again, we'll conclude that we've seen the whole
         * chain before when in fact we haven't. But this should be rare.)
         */

 * </ul>
 *
 * To force selection of our fallback strategies we load {@link AbstractFuture} (and all of {@code
 * com.google.common.util.concurrent}) in degenerate class loaders which make certain platform
 * classes unavailable. Then we construct a test suite so we can run the normal AbstractFutureTest
 * test methods in these degenerate classloaders.
 */

      } finally {
        monitor.leave();
      }
    } else {
      // It is possible due to races that we are currently in the expected state even though we
      // timed out. e.g. if we weren't event able to grab the lock within the timeout we would never
      // even check the guard. I don't think we care too much about this use case but it could lead
      // to a confusing error message.

            <!-- Even after we stop using JSR305 annotations in our own code, we'll want this link so that NullPointerTester's docs can link to @CheckForNull and friends... at least once we start using this config for guava-testlib. -->
            <offlineLink>

Let's continue from the previous example. We wanted to **annotate the function with one type** but return something that includes **more data**.

We want FastAPI to keep **filtering** the data using the response model.

In the previous example, because the classes were different, we had to use the `response_model` parameter. But that also means that we don't get the support from the editor and tools checking the function return type.

    lock.assertHeld()

    // If this connection is not accepting new exchanges, we're done.
    if (calls.size >= allocationLimit || noNewExchanges) return false

    // If the non-host fields of the address don't overlap, we're done.
    if (!this.route.address.equalsNonHost(address)) return false

    // If the host exactly matches, we're done: this connection can carry the address.