What version of SDDM is included with SQL Developer 4.0 EA2? Is git supported for SDDM designs?
you can check version of Data Modeler using "Help>About" and then export to (clipboard or file). You'll find the record for Data Modeler:
Oracle SQL Developer Data Modeler oracle.datamodeler 188.8.131.528
There is no integrated support for git. If you want to use git then you always can look at design simply as set of files and directories.