Are cycles allowed between platform modules?

This is the module declaration of the java.rmi module:

module java.rmi {
    requires java.base;
    requires java.logging;

    exports java.rmi.activation;
    exports com.sun.rmi.rmid to java.base; // <-- cycle
    ...
}

So, there is a cyclic dependency between java.rmi and java.base, right? Are cycles allowed between platform modules?