Note from Frederic:

During last week meetings in Burlington, it has been decided that
the language should not prohibit user from creating cycles with
flattenable fields. Instead, the JVM should detect cycles and
manage flattening decision in a way to avoid infinite recursion
(basically by not flattening a field in a cycle).

I already have implemented most of the new semantic in the
JVM. However, javac currently refuses to compile source
with cycles of flattenable fields, because it still complies to
the old semantic. This mean that we have to use manually
crafted or modified class files in order to test the new code.

Would it be possible to have the option to relax the circularity
rules on javac, so testing would be easier for us? Eventually,
javac would have to switch to the new semantic once we have
proven that the JVM is capable to handle cycles on its own.