Yeti and Arnold or V-Ray motion blur bug fix

If you need to get a working motion blur using V-Ray or Arnold and you have had such problems:

V-ray (normal/with bug)

you need to make a few changes.
If you use in your Yeti tree any expressions with Position attribute (P) then you need:
For Yeti 2.1.xx
1. for all objects from which you get P attribute you need create texture reference objects;
2. replace all P on Pref
For Yeti 2.2
1. the same step as for Yeti 2.1.xx
2. P -> Pundef

If you have this bug and you use VRay, then render time increase approximately x3.3