@Override
    public List<ParamInfo> getParamInfo() {
        return List.of(
                ParamInfo.optionalParam(PARAM_NAME_LIMIT,
                        "A limit on the number of keys to return, default is unlimited."));
    }
@return The number of keys in the pool cache
stroom-pipeline/src/main/java/stroom/pipeline/cache/AbstractPoolCache.java