docs: @PublicEvolving
  	public <KS, OUT> SingleOutputStreamOperator<OUT> process(
  			final KeyedBroadcastProcessFunction<KS, IN1, IN2, OUT> function,
  			final TypeInformation<OUT> outTypeInfo) {
  
  		Preconditions.checkNotNull(function);
  		Preconditions.checkArgument(inputStream1 instanceof KeyedStream,
  				"A KeyedBroadcastProcessFunction can only be used on a keyed stream.");
  
  		TwoInputStreamOperator<IN1, IN2, OUT> operator =
  				new CoBroadcastWithKeyedOperator<>(clean(function), broadcastStateDescriptors);
  		return transform("Co-Process-Broadcast-Keyed", outTypeInfo, operator);
  	}