Regression: all uppercase field reference results in compile error

Consider the following ways of writing getters, setters and pattern field names

element xetter field 5.1.1 5.3.0
=============================================
state xetstate state OK OK
state xetState state OK OK
staTe xetStaTe staTe OK OK
state xetSTATE STATE OK ERR

The last variation is a regression from 5.1.1. It is not so absurd - if the field is designated with an acronym (XML,...) this would be the natural way to write xetters and the pattern field.