You can clone with
HTTPS or Subversion.
DataNucleus, a popular and versatile persistence tool, employs a plugin architecture for underlying data stores.
This request is for OrientDB to supply an official DataNucleus plugin so that existing and new DataNucleus JDO & JPA codebases can use OrientDB as the underlying data store.
See forum discussion at https://groups.google.com/forum/?fromgroups=#!topic/orient-database/GMP2RRIYWqo
You might consider starting by copying DataNucleus's Neo4j plugin. See http://www.datanucleus.org/plugins/store.neo4j.html, which includes a link to the source repo location.
We've not enough resource to invest here, sorry.