@Override
    public String getDisplayName() {
        return displayName;
    }
User identity for a service user for this application to authenticate with other
applications on the same IDP realm. I.e. Stroom's processing user.
This user uses the client credentials flow.
stroom-security/stroom-security-common-impl/src/main/java/stroom/security/common/impl/ServiceUserIdentity.java