@Override
    public String toString() {
        return "DataFeedKeyUserIdentity{" +
               "subjectId='" + subjectId + '\'' +
               ", displayName='" + displayName + '\'' +
               '}';
    }
{@link UserIdentity} obtained when authenticated by {@link HashedDataFeedKey}
stroom-receive/stroom-receive-common/src/main/java/stroom/receive/common/DataFeedKeyUserIdentity.java