code: public CMAUpload fetchOne(String spaceId, String uploadId) {
      assertNotNull(spaceId, "spaceId");
      assertNotNull(uploadId, "uploadId");
  
      return service.fetchOne(spaceId, uploadId).blockingFirst();
    }
docs: Get information about the given upload.
  <p>
  This method will override the configuration specified through
  {@link CMAClient.Builder#setSpaceId(String)} and will ignore
  {@link CMAClient.Builder#setEnvironmentId(String)}.
  
  @param spaceId  which space is this upload hosted under?
  @param uploadId what id does the upload have?
  @return an CMAUpload based on this id and space combination.
  @throws IllegalArgumentException if spaceId is null.
  @throws IllegalArgumentException if uploadId is null.