public void addJoint(PhysicsJoint joint) {
        if (!joints.contains(joint)) {
            joints.add(joint);
        }
    }
do not use manually, joints are added automatically

@param joint the joint to add (not null, alias created)
jme3-jbullet/src/main/java/com/jme3/bullet/objects/PhysicsRigidBody.java