code: public void addUser(String poolId, String nodeId, ComputeNodeUser user) {
          addUserWithServiceResponseAsync(poolId, nodeId, user).toBlocking().single().body();
      }
docs: Adds a user account to the specified compute node.
  You can add a user account to a node only when it is in the idle or running state.
  
  @param poolId The ID of the pool that contains the compute node.
  @param nodeId The ID of the machine on which you want to create a user account.
  @param user The user account to be created.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @throws BatchErrorException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent