如何检查flink中的DataStream为空或有数据

DataStream<T> dataStream = ...; // 输入的DataStream
DataStream<T> nonEmptyDataStream = dataStream.filter(data -> data != null);

DataStream<T> dataStream = ...; // 输入的DataStream
boolean isEmpty = dataStream.isEmpty().get();

DataStream<T> dataStream = ...; // 输入的DataStream
long count = dataStream.count();
boolean isEmpty = count == 0;