/** The key of the configuration. e.g. https://repo.maven.apache.org/maven2/org/codelibs/fess/,https://fess.codelibs.org/plugin/artifacts.yaml */
    String PLUGIN_REPOSITORIES = "plugin.repositories";

    /** The key of the configuration. e.g.  */
    String PLUGIN_VERSION_FILTER = "plugin.version.filter";

    /** The key of the configuration. e.g. 1000 */