code: public List<String> getRunningWorkflow(String workflowName, @Nullable Integer version) {
          Preconditions.checkArgument(StringUtils.isNotBlank(workflowName), "Workflow name cannot be blank");
  
          WorkflowServicePb.GetRunningWorkflowsResponse workflows = stub.getRunningWorkflows(
                  WorkflowServicePb.GetRunningWorkflowsRequest.newBuilder()
                          .setName(workflowName)
                          .setVersion(version == null ? 1 : version)
                          .build()
          );
          return workflows.getWorkflowIdsList();
      }
docs: /*
  Retrieve all running workflow instances for a given name and version
  
  @param workflowName the name of the workflow
  @param version      the version of the wokflow definition. Defaults to 1.
  @return the list of running workflow instances