...
MembershipSave membershipSave = new MembershipSave().assignGroup(group1).assignSubject(subject).assignSaveMode(SaveMode.DELETE); membershipSave.save();
Sample call to add a membership using group name and subject identifier and sourceId. Note, use double quotes to be java compliant
new MembershipSave().assignGroupName('a:b:c').assignSubjectIdentifier('jsmith').assignSubjectSourceId('myUsers').save();