Questions about feature statemachine

While I try to learn how the Qt feature system works to introduce new features I try to play with the feature "statemachine". But whatever I do, the statemachine is always build.

• QT_FEATURE_statemachine is always empty/unset.
• Configure option "-feature-statemachine" does not change anything.
• Configure option "-no-feature-statemachine" does not change anything.
• When I try to exclude the folders in qtscxml/src/CMakeLists.txt based on QT_FEATURE_statemachine it is never build.

Playing with the feature "scxml-ecmascriptdatamodel" works great.

• QT_FEATURE_scxml_ecmascriptdatamodel is "ON" in general.
• It is empty/unset when "no-feature-scxml-ecmascriptdatamodel" is used in configuration.

Would be nice if anyone can give me a hint. I try a lot of things to make it work but nothing helps.