public StreamStreamJoinNode<K, V1, V2, VR> build() {

            return new StreamStreamJoinNode<>(nodeName,
                                              valueJoiner,
                                              joinThisProcessorParameters,
                                              joinOtherProcessorParameters,
                                              joinMergeProcessorParameters,
                                              thisWindowedStreamProcessorParameters,
                                              otherWindowedStreamProcessorParameters,
                                              thisStoreFactory,
                                              otherStoreFactory,
                                              outerJoinStoreFactory,
                                              joined,
                                              enableSpuriousResultFix,
                                              selfJoinProcessorParameters);


        }
Too much information to generalize, so Stream-Stream joins are represented by a specific node.
streams/src/main/java/org/apache/kafka/streams/kstream/internals/graph/StreamStreamJoinNode.java