code: protected <S extends State, N> S getPartitionedState(
  			N namespace,
  			TypeSerializer<N> namespaceSerializer,
  			StateDescriptor<S, ?> stateDescriptor) throws Exception {
  
  		/*
  	    TODO: NOTE: This method does a lot of work caching / retrieving states just to update the namespace.
  	    This method should be removed for the sake of namespaces being lazily fetched from the keyed
  	    state backend, or being set on the state directly.
  	    */
  
  		if (keyedStateStore != null) {
  			return keyedStateBackend.getPartitionedState(namespace, namespaceSerializer, stateDescriptor);
  		} else {
  			throw new RuntimeException("Cannot create partitioned state. The keyed state " +
  				"backend has not been set. This indicates that the operator is not " +
  				"partitioned/keyed.");
  		}
  	}
docs: Creates a partitioned state handle, using the state backend configured for this task.
  
  @throws IllegalStateException Thrown, if the key/value state was already initialized.
  @throws Exception Thrown, if the state backend cannot create the key/value state.