iiop-openjdk/src/main/java/org/wildfly/iiop/openjdk/security/TrustedIdentityTokenLoginModule.java
protected void validateCredential(final String username, final SASCurrent credential) throws LoginException {
        if (credential.get_incoming_principal_name() == null ||
                credential.get_incoming_principal_name().length == 0) {
            throw new LoginException();
        }
    }
protected void validateCredential(final String username, final SASCurrent credential) throws LoginException {
        if (credential.get_incoming_principal_name() == null ||
                credential.get_incoming_principal_name().length == 0) {
            throw new LoginException();
        }
    }
Validates the credential. Unfortunately there is not much we can do here by default.
<p/>
This method can be overridden to provide some real validation logic

@param username   The username
@param credential The SASCurrent.