How to make leftJoin for KTable Many To One?

Question

I have two Ktable and I need doing leftJoin. This left join mast be ManyToOne. I have next code for leftJoin:

KTable<String, GenericRecord> right = createKTable("topic_1");
KTable<String, GenericRecord> left = createKTable("topic_2");

KTable<String, GenericRecord> joined = right.leftJoin(left, (doc, infoReg) -> {
            List<Schema.Field> fields = doc.getSchema().getFields();
            GenericRecord resultRecords = new GenericData.Record(valueSchema);

            for (Schema.Field field : fields) {
                resultRecords.put(field.name(), doc.get(field.name()));
            }
            Schema schema = valueSchema.getField("InfoReg").schema();
            GenericArray<GenericRecord> list = new GenericData.Array<>(0, schema);
                list.add(infoReg);
                resultRecords.put("InfoReg", list);

            return resultRecords;
        });

But it's work like OneToOne. How I can change code for ManyToOne?

Check out the docs: https://kafka.apache.org/25/documentation/streams/developer-guide/dsl-api.html#ktable-ktable-fk-join — Matthias J. Sax, Jun 06 '20 at 20:43
Thank you, but I don’t understand how this will help to join many-to-one. Could you explain? — Леонид Дубравский, Jun 07 '20 at 10:50
A foreign-key join is a 1-n-join -- it's just a different name for the same thing. The example shows this with rows 7/8/9: There are two rows `(r,10)` and `(q,10)` in the left table and both join with `(10,baz)` from the right table. — Matthias J. Sax, Jun 07 '20 at 20:32

How to make leftJoin for KTable Many To One?

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