code: public CreateThumbnailJobResponse createThumbnailJob(String pipelineName, String sourceKey) {
          ThumbnailSource source = new ThumbnailSource();
          source.setKey(sourceKey);
          
          CreateThumbnailJobRequest request =
                  new CreateThumbnailJobRequest().withPipelineName(pipelineName).withSource(source);
          
          return createThumbnailJob(request);
      }
docs: Creates a thumbnail job and return job ID.
  
  @param pipelineName The name of a pipeline.
  @param sourceKey The key of source object.
  
  @return the unique ID of the new thumbnail job.