docs: public SendMessageBatchResult withSuccessful(SendMessageBatchResultEntry... successful) {
          if (this.successful == null) {
              setSuccessful(new com.amazonaws.internal.SdkInternalList<SendMessageBatchResultEntry>(successful.length));
          }
          for (SendMessageBatchResultEntry ele : successful) {
              this.successful.add(ele);
          }
          return this;
      }