docs: public Waiter<DescribeKeyPairsRequest> keyPairExists() {
  
          return new WaiterBuilder<DescribeKeyPairsRequest, DescribeKeyPairsResult>().withSdkFunction(new DescribeKeyPairsFunction(client))
                  .withAcceptors(new KeyPairExists.IsTrueMatcher(), new KeyPairExists.IsInvalidKeyPairNotFoundMatcher())
                  .withDefaultPollingStrategy(new PollingStrategy(new MaxAttemptsRetryStrategy(6), new FixedDelayStrategy(5)))
                  .withExecutorService(executorService).build();
      }