TapCient tapBackFill issue

Trying to use TapClient in my project. Throwing exception while using tapBackFill method of TapClient class 'ArrayIndexOutOfBoundsException : 24 '. Using couchbase-client-1.4.13 jar and spymemcached-2.12.3 jar. These are the latest ones.

The TAP protocol was removed in Couchbase Server 5.0 - see https://docs.couchbase.com/server/5.0/release-notes/relnotes.html#release-500