Github user fhueske commented on a diff in the pull request: https://github.com/apache/flink/pull/4625#discussion_r142681890 --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/nodes/datastream/DataStreamWindowJoin.scala --- @@ -152,19 +176,40 @@ class DataStreamWindowJoin( } } - def createProcTimeInnerJoinFunction( + def createEmptyInnerJoin( + leftDataStream: DataStream[CRow], + rightDataStream: DataStream[CRow], + returnTypeInfo: TypeInformation[CRow]) = { + leftDataStream.connect(rightDataStream).process( + new CoProcessFunction[CRow, CRow, CRow] { + override def processElement1( --- End diff -- add `Unit` return types for both `processElement` methods.
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