code: public Observable<ImageRegionProposal> getImageRegionProposalsAsync(UUID projectId, UUID imageId) {
          return getImageRegionProposalsWithServiceResponseAsync(projectId, imageId).map(new Func1<ServiceResponse<ImageRegionProposal>, ImageRegionProposal>() {
              @Override
              public ImageRegionProposal call(ServiceResponse<ImageRegionProposal> response) {
                  return response.body();
              }
          });
      }
docs: Get region proposals for an image. Returns empty array if no proposals are found.
  This API will get region proposals for an image along with confidences for the region. It returns an empty array if no proposals are found.
  
  @param projectId The project id
  @param imageId The image id
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the ImageRegionProposal object