code: public void beginStartEnvironment(String userName, String environmentId) {
          beginStartEnvironmentWithServiceResponseAsync(userName, environmentId).toBlocking().single().body();
      }
docs: Starts an environment by starting all resources inside the environment. This operation can take a while to complete.
  
  @param userName The name of the user.
  @param environmentId The resourceId of the environment
  @throws IllegalArgumentException thrown if parameters fail the validation
  @throws CloudException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent