In the Groovy in Action book, chapter 8.4.5 says
Category method names can well take the form of property accessors (pretending property access), operator methods, and GroovyObject methods. MOP hook methods cannot be added through a category class. This is a restriction as of Groovy 2.4. The feature may become available in later versions.
It interpreted this as meaning that I can add GroovyMethods (getProperty,
getMetaClass, invokeMethod , setMetaClass and setProperty) to a class using categories but not
methodMissing or propertyMissing (which I think they call MOP hook methods in the GINA book).
But when I tried to add invokeMethod using a category the change has no effect, adding missingMethod does not work either see attachement.
I see that methodsMissing/ propertyMissing via category was probably never supported noted in
GROOVY-3867. But the Groovy in Action paragraph makes me think that invokeMethod et al were supported at some point.