* configuration and discovery in protocols like SAML.
     */
    METADATA,

    /**
     * Indicates a request to perform a logout operation, terminating the
     * user's SSO session.
     */
    LOGOUT;

    result.write(this, i)
    // Consume '\'.
    readByte()
    result.write(this, 1L) // The escaped character.
  }
}

/**
 * Consumes and returns a non-empty token, terminating at special characters in
 * [TOKEN_DELIMITERS]. Returns null if the buffer is empty or prefixed with a delimiter.
 */
private fun Buffer.readToken(): String? {
  var tokenSize = indexOfElement(TOKEN_DELIMITERS)

Since HTTP requests frequently happen in parallel, connection pooling must be thread-safe.

These are the primary classes involved with establishing, sharing, and terminating connections:

 * **RealConnectionPool** manages reuse of HTTP and HTTP/2 connections for reduced latency. Every OkHttpClient has one, and its lifetime spans the lifetime of the OkHttpClient.

   *   ...
   * </pre>
   *
   * <p>The returned handler logs any exception at severity {@code SEVERE} and then shuts down the
   * process with an exit status of 1, indicating abnormal termination.
   */
  public static UncaughtExceptionHandler systemExit() {
    return new Exiter(Runtime.getRuntime()::exit);
  }

  @VisibleForTesting
  interface RuntimeWrapper {
    void exit(int status);
  }

   *   ...
   * </pre>
   *
   * <p>The returned handler logs any exception at severity {@code SEVERE} and then shuts down the
   * process with an exit status of 1, indicating abnormal termination.
   */
  public static UncaughtExceptionHandler systemExit() {
    return new Exiter(Runtime.getRuntime()::exit);
  }

  @VisibleForTesting
  interface RuntimeWrapper {
    void exit(int status);
  }

   *
   * <p>Although all tasks are immediately executed in the thread that submitted the task, this
   * {@code ExecutorService} imposes a small locking overhead on each task submission in order to
   * implement shutdown and termination behavior.
   *
   * <p>Because of the nature of single-thread execution, the methods {@code scheduleAtFixedRate}
   * and {@code scheduleWithFixedDelay} are not supported by this class and will throw an

 * with the abstract {@link #execute execute(Runnable)} method.
 *
 * <p>In addition to {@link #execute}, subclasses must implement all methods related to shutdown and
 * termination.
 *
 * @author Chris Povirk
 * @since 14.0
 */
@CheckReturnValue
@GwtIncompatible
public abstract class AbstractListeningExecutorService extends AbstractExecutorService
    implements ListeningExecutorService {

   * linefeed ({@code "\r\n"}).
   *
   * @return a {@code String} containing the contents of the line, not including any
   *     line-termination characters, or {@code null} if the end of the stream has been reached.
   * @throws IOException if an I/O error occurs
   */
  @CanIgnoreReturnValue // to skip a line
  public @Nullable String readLine() throws IOException {

    return asCharSource(url, charset).readLines(callback);
  }

  /**
   * Reads all of the lines from a URL. The lines do not include line-termination characters, but do
   * include other leading and trailing whitespace.
   *
   * <p>This method returns a mutable {@code List}. For an {@code ImmutableList}, use {@code

   *
   * <p>Although all tasks are immediately executed in the thread that submitted the task, this
   * {@code ExecutorService} imposes a small locking overhead on each task submission in order to
   * implement shutdown and termination behavior.
   *
   * <p>Because of the nature of single-thread execution, the methods {@code scheduleAtFixedRate}
   * and {@code scheduleWithFixedDelay} are not supported by this class and will throw an