Here is a proposal to add support for SSH authentication for Git persistence:

https://github.com/wildfly/wildfly-proposals/pull/249

This is being handled under the following Jira issues:

https://issues.jboss.org/browse/ELY-1879
https://issues.jboss.org/browse/WFCORE-4484
https://issues.jboss.org/browse/WFLY-12574

Regards,
Ashley Abdel-Sayed