docs: void beginPartUpload(final int nextPartNumber)
              throws SdkClientException {
          if (nextPartNumber < 1)
              throw new IllegalArgumentException("part number must be at least 1");
          if (partUploadInProgress) {
              throw new SdkClientException(
                      "Parts are required to be uploaded in series");
          }
          synchronized (this) {
              if (nextPartNumber - partNumber <= 1) {
                  partNumber = nextPartNumber;
                  partUploadInProgress = true;
              } else {
                  throw new SdkClientException(
                          "Parts are required to be uploaded in series (partNumber="
                                  + partNumber + ", nextPartNumber="
                                  + nextPartNumber + ")");
              }
          }
      }