code: public Observable<ProjectFileInner> getAsync(String groupName, String serviceName, String projectName, String fileName) {
          return getWithServiceResponseAsync(groupName, serviceName, projectName, fileName).map(new Func1<ServiceResponse<ProjectFileInner>, ProjectFileInner>() {
              @Override
              public ProjectFileInner call(ServiceResponse<ProjectFileInner> response) {
                  return response.body();
              }
          });
      }
docs: Get file information.
  The files resource is a nested, proxy-only resource representing a file stored under the project resource. This method retrieves information about a file.
  
  @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 ProjectFileInner object