Following the previsous raised Bug JRA-31063, closed for duplication with JRA-30451, I am always not able to migrate my Mail Handler from 5.1 to any JIRA 5.2.x to 6.2.2.

With 6.2.2, my plugin is not loadable due to a non exported package : com.atlassian.jira.plugins.mail.extensions.
I need to use it for the the validator-class com.atlassian.jira.plugins.mail.extensions.ProjectRequiredMessageHandlerValidator or implement my own Validator (interface MessageHandlerValidator).

How can I resolve it ???