}
          // TODO(cpovirk): if reference has been cleared, remove it?
        }
        checkExceptionClassValidity(exceptionClass);

        /*
         * It's very unlikely that any loaded Futures class will see getChecked called with more
         * than a handful of exceptions. But it seems prudent to set a cap on how many we'll cache.
         * This avoids out-of-control memory consumption, and it keeps the cache from growing so

 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *

    public static final String CHILDREN_COMBINATION_APPEND = "append";
    /**
     * Default mode for combining children DOMs during merge.
     * When element names match, the process will try to merge the element data,
     * rather than putting the dominant and recessive elements as siblings.
     */
    public static final String DEFAULT_CHILDREN_COMBINATION_MODE = CHILDREN_COMBINATION_MERGE;

        // Here, we need to determine which policy to use. Release updateInterval will be used when
        // the metadata refers to a release artifact or meta-version, and snapshot updateInterval will be used when
        // it refers to a snapshot artifact or meta-version.

 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *

 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *

// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//

     * Constructs a new request.
     */
    public Request() {
        // nothing
    }

    /**
     * Executes the request.
     * @param client The OpenSearch client.
     * @return A Promise that will be resolved with the response or rejected with an error.
     */
    public Deferred<T>.Promise execute(final Client client) {
        final String error = getValidationError();
        if (!Strings.isNullOrEmpty(error)) {

 * that is currently executing does not impact the ongoing run, but it does prevent a recurrence
 * from being scheduled.
 *
 * Tasks may opt-out of cancellation with `cancelable = false`. Such tasks will recur until they
 * decide not to by returning -1L.
 *
 * Task Queues
 * -----------
 *
 * Tasks are bound to the [TaskQueue] they are scheduled in. Each queue is sequential and the tasks

   * sneaky checked exception.
   *
   * @return never; this method declares a return type of {@link Error} only so that callers can
   *     write {@code throw sneakyThrow(t);} to convince the compiler that the statement will always
   *     throw.
   */
  @CanIgnoreReturnValue
  static Error sneakyThrow(Throwable t) {
    throw new SneakyThrows<Error>().throwIt(t);
  }