public Matrix3f getPhysicsRotationMatrix(Matrix3f rotation) {
        if (rotation == null) {
            rotation = new Matrix3f();
        }
        rBody.getCenterOfMassTransform(tempTrans);
        return Converter.convert(tempTrans.basis, rotation);
    }
Gets the physics object rotation as a matrix, no conversions and no object instantiation
@param rotation the rotation of the actual physics object is stored in this Matrix3f
@return a rotation matrix (in physics-space coordinates, either
rotation or a new matrix)
jme3-jbullet/src/main/java/com/jme3/bullet/objects/PhysicsRigidBody.java