[wildfly-dev] Adding attributes where the default value is different from the legacy implied behaviour

The https://github.com/wildfly/wildfly/pull/5460 (and the linked PR within) below illustrates the ‘problem’. Although Infinispan is where this popped up, this is bound to have happened in other places as well. The latest version of the infinispan subsystem adds a boolean ‘statistics’ which allows us to turn off statistics gathering in the infinispan subsystem. Previously this was always on, i.e. ’true’. We want the user to have to explicitly turn it on, so its default value is ‘false’. However, in the old parsers, it struck me that they do not expose this attribute in their versions of the xsd, and so they before https://github.com/wildfly/wildfly/pull/5460 would have ended up always not setting the attribute, which means ‘false’. This is different behaviour than running the old xml in an older version of AS where this would have resulted in ‘true’, hence this fix.