code: public Observable<ComapiResult<UploadContentResponse>> uploadContent(@NonNull final String folder, @NonNull final ContentData data) {
  
          final String token = getToken();
  
          if (sessionController.isCreatingSession()) {
              return getTaskQueue().queueUploadContent(folder, data);
          } else if (TextUtils.isEmpty(token)) {
              return Observable.error(getSessionStateErrorDescription());
          } else {
              return doUploadContent(token, folder, data.getName(), data);
          }
      }
docs: Upload content data.
  
  @param folder Folder name to put the file in.
  @param data   Content data.
  @return Observable emitting details of uploaded content.