Calling getNegotiatedProperty for Elytron SASL mechanisms doesn't throw IllegalStateException when negotiatition is not completed

The Elytron SASL mechanism implementations don't throw IllegalStateException when calling the getNegotiatedProperty() method before the negotiation is finished.

The contract of the Object javax.security.sasl.SaslClient.getNegotiatedProperty(String propName) says:

Retrieves the negotiated property. This method can be called only after the authentication exchange has completed (i.e., when isComplete() returns true); otherwise, an IllegalStateException is thrown.

The same is valid for the SaslServer interface.