They are allowed since IDEA 5.0 in java modules, but currently forbidden in J2EE modules.
I don't know if the J2EE spec explicitly forbids them or not, but i happen to have to work on a quite old project that has some, and I do not have authorization to do the (very large) refactorings that would be needed to get rid of them.
This project has been created originally using IBM WSAD which managed to create an EAR for the project. and Websphere accepts the ear.
I managed to create the cyclic dependencies in the IDEA projects using "import eclipse workspace" feature, but now i can't modify the classpaths anymore as IDEA refuses to modify them if the cyclic dependencies exists.
Any chance to have IDEA accept cyclic dependencies between J2EE modules ?