code: public Observable<FileStorageInfoInner> readAsync(String groupName, String serviceName, String projectName, String fileName) {
          return readWithServiceResponseAsync(groupName, serviceName, projectName, fileName).map(new Func1<ServiceResponse<FileStorageInfoInner>, FileStorageInfoInner>() {
              @Override
              public FileStorageInfoInner call(ServiceResponse<FileStorageInfoInner> response) {
                  return response.body();
              }
          });
      }
docs: Request storage information for downloading the file content.
  This method is used for requesting storage information using which contents of the file can be downloaded.
  
  @param groupName Name of the resource group
  @param serviceName Name of the service
  @param projectName Name of the project
  @param fileName Name of the File
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the FileStorageInfoInner object