code: @Override
      public String update(EntityUpdateOperation updater) throws ServiceException {
          updater.setProxyData(createProxyData());
          ClientResponse clientResponse = getResource(updater).header("X-HTTP-METHOD",
                  "MERGE").post(ClientResponse.class,
                  updater.getRequestContents());
          PipelineHelpers.throwIfNotSuccess(clientResponse);
          updater.processResponse(clientResponse);
          if (clientResponse.getHeaders().containsKey("operation-id")) {
              List<String> operationIds = clientResponse.getHeaders().get("operation-id");
              if (operationIds.size() >= 0) {
                  return operationIds.get(0);
              }
          }
          return null;
      }
docs: /*
  (non-Javadoc)
  
  @see
  com.microsoft.windowsazure.services.media.entityoperations.EntityContract
  #update(com.microsoft.windowsazure.services.media.entityoperations.
  EntityUpdateOperation)