Primary keepalive message not appearing in Logical Streaming Replication

Implemented the Logical Streaming Replication thing are working fine I see
the XLogData message appearing and I'm able to parse them.

But I haven't see any "Primary Keepalive message"  yet. I had tried setting
the *tcp_keepalive_interval*, *tcp_keepalives_idle* both from client
runtime paramter and well as from postgresql.conf still no clue of it.

Any information around it?

If it help I had use the wal2json shared_libraries to send json data across
in the stream.