public static UnboundStringFlag defineStringFlag(String flagId, String defaultValue, List<String> owners,
                                                     String createdAt, String expiresAt, String description,
                                                     String modificationEffect, Dimension... dimensions) {
        return defineStringFlag(flagId, defaultValue, owners,
                                createdAt, expiresAt, description,
                                modificationEffect, value -> true,
                                dimensions);
    }
WARNING: public for testing: All flags should be defined in {@link Flags}.
flags/src/main/java/com/yahoo/vespa/flags/Flags.java