groovydoc information loss for enums

-------------------------------
$ groovydoc --version
GroovyDoc 2.1.6
$ cat > Foo.groovy <<EOF
enum Foo {
A, B, C, D
}
EOF
$ groovydoc Foo.groovy
$ open index.html
-------------------------------

Problem: generated GAPI doesn't show enumerated values of `Foo` (A, B, C, D).

Further information:
http://groovy.329449.n5.nabble.com/groovydoc-information-loss-for-enums-and-generics-td5716165.html