SSO with OpenID and MITREid Connect

We are implementing Single Sign On (SSO) with OpenID and would like to use an alternative IDP created on the basis of MITREid Connect (
The documentation mentions several vendors and only one open, Kopano Konnect which is written in GO, we would like to use a Java version instead.
Does anyone know whether ‘custom’ solutions can still be connected to OwnCloud?
Theoretically if they are based on OpenID they should all work, but if you know of open solutions in Java that integrate easily please let me know, thank you very much!