IntervalJoin基于connect实现，期间会生成对应的IntervalJoinOperator。@PublicEvolvingpublicOUT>SingleOutputStreamOperatorOUT>process(ProcessJoinFunctionIN1,IN2,OUT>processJoinFunction,TypeInformationOUT>outputType){Preconditions.checkNotNull(processJoinFunction);Preconditions.checkNotNull(outputType);//检查用户自定义Functi