in src/main/java/com/googlesource/gerrit/plugins/javamelody/GerritMonitoringFilter.java [127:139]
    public void init(FilterConfig config) throws ServletException {
      if (isPropertyInPluginConfig(HTTP_TRANSFORM_PATTERN)
          || isPropertyUndefined(config, HTTP_TRANSFORM_PATTERN, GLOBAL_HTTP_TRANSFORM_PATTERN)) {
        System.setProperty(GLOBAL_HTTP_TRANSFORM_PATTERN, getTransformPattern());
      }
      if (isPropertyInPluginConfig(STORAGE_DIR)
          || isPropertyUndefined(config, STORAGE_DIR, GLOBAL_STORAGE_DIR)) {
        System.setProperty(GLOBAL_STORAGE_DIR, getStorageDir());
      }
      super.init(config);
    }