Within the AST almost all nodes refer to a source code position.

This position is almost always set using setOffsetAndLength(), sometimes using another ASTNote.

I propose a Value Object for presenting such source locations and use that throughout.

May be an integration/substitution other "location" classes is feasable and those should be used instead.

class Location might as an immutable class just be OK. It might even provide more functionality than access to the fields as of today.

E.g. "arithmetic" on intervals to join or check for overlap.