public Quaternion getPhysicsRotation(){
        return getPhysicsRotation(null);
    }
Gets the physics object rotation as a quaternion, converts the bullet Matrix3f value,
instantiates new object

@return a new rotation Quaternion (in physics-space coordinates)
jme3-jbullet/src/main/java/com/jme3/bullet/objects/PhysicsRigidBody.java