In the case of our project, the environment that generates a JSON from a RexNode and the environment that reads it are different. We need to "translate" the inputs into their aliases in the new cluster.
This method will permit to give more freedom to the JSON RexNode parser if needed.
* Transforms a RexNode tree defined in a map (from a JSON) into a RexNode
* Applying a special method to inputs instead of transforming them into inputRef
* @param cluster The optimization environment
* @param apply is a InputTranslator lambda that transforms the map representing input
* references into a RexNode
* @param o the map derived from a RexNode transformed into a JSON
* @return the transformed RexNode
Make sure that RexNode toRex(RelInput relInput, @PolyNull Object o) is still working + adding tests