Repository repository = RepositoryReferenceFactory.getRepository("test-inmemory");
Session session = repository.login();
VersionManager vm = session.getWorkspace().getVersionManager();
		
Node outer = session.getRootNode().addNode("outerFolder");
Node inner = outer.addNode("innerFolder");
Node file  = inner.addNode("testFile.dat");
file.setProperty("jcr:mimeType", "text/plain");
file.setProperty("jcr:data", "Original content");
session.save();
		
isVersionable(vm, file);
file.addMixin("mix:versionable");
session.refresh(true);
isVersionable(vm, file);

boolean isVersionable(VersionManager vm, Node node) throws RepositoryException {
    try {
        vm.getVersionHistory(node.getPath());
        return true;
    } catch (UnsupportedRepositoryOperationException e) {
        return false;
    }
}