docs: @PublicEvolving
  	public QueryableStateStream<KEY, T> asQueryableState(
  			String queryableStateName,
  			ReducingStateDescriptor<T> stateDescriptor) {
  
  		transform("Queryable state: " + queryableStateName,
  				getType(),
  				new QueryableAppendingStateOperator<>(queryableStateName, stateDescriptor));
  
  		stateDescriptor.initializeSerializerUnlessSet(getExecutionConfig());
  
  		return new QueryableStateStream<>(
  				queryableStateName,
  				stateDescriptor,
  				getKeyType().createSerializer(getExecutionConfig()));
  	}