JDBC driver returns different version strings on Ubuntu and CentOS

I have just noticed that DatabaseMetaData.getDatabaseProductVersion() returns the String "10.2.2" when connected to a
serverrunning on Ubuntu, but returns "10.2" when connected to a server running on CentOS or Windows. 
 

Is there a specific reason for this? 

It's a bit confusing because 10.2.2 doesn't actually exists as a "real" Postgres version.

This happens with the driver versions 42.1.4 and 42.2.1 (haven tried others)

Regards
Thomas