public Quaternion getPhysicsRotation(Quaternion rotation){
        if (rotation == null) {
            rotation = new Quaternion();
        }
        rBody.getCenterOfMassTransform(tempTrans);
        return Converter.convert(tempTrans.basis, rotation);
    }
Gets the physics object rotation as a quaternion, converts the bullet Matrix3f value
@param rotation the rotation of the actual physics object is stored in this Quaternion
@return a rotation Quaternion (in physics-space coordinates, either
rotation or a new instance)
jme3-jbullet/src/main/java/com/jme3/bullet/objects/PhysicsRigidBody.java