Custom world generation/position source

** : The namespaced id of the position source type. Must be one of block and entity.
**; If type is block, additional field is as follow:
** : The block position.
*** : X.
*** : Y.
*** : Z.
**; If type is entity, additional fields are as follows:
** : The int-array UUID of an entity.
*** 
*** 
*** 
*** 
** : (optional, defaults to 0.0) The Y offset from entity's feet.
Category:Java Edition
Category:Data packs