* generates a synthetic method for the body of the lambda, the actual method calls that Animal
   * Sniffer is flagging don't appear inside toImmutableSortedMultiset but rather inside that
   * synthetic method. By moving those calls to a named method, we're able to apply
   * @IgnoreJRERequirement somewhere that it will help.
   */
  private static <T extends @Nullable Object, E> void mapAndAdd(