subject.getPrivateCredentials returns null in EAP 5

Issue

• Trying to get the user's password after they've been authenticated so it can be passed to other web services that require this password. I retrieve the Principal and Role info great, but get nothing when calling getPrivateCredentials() or getPublicCredentials() on subject it returns null.
• How can I access the user's password in EAP 5 in my application?