code: public ModelNode registerDeploymentSubsystemResource(final String subsystemName, final Resource resource) {
          assert subsystemName != null : "The subsystemName cannot be null";
          assert resource != null : "The resource cannot be null";
          return registerDeploymentSubResource(subsystemName, PathAddress.EMPTY_ADDRESS, resource);
      }
docs: Registers the resource to the parent deployment resource. The model returned is that of the resource parameter.
  
  @param subsystemName the subsystem name
  @param resource      the resource to be used for the subsystem on the deployment
  
  @return the model
  
  @throws java.lang.IllegalStateException if the subsystem resource already exists