private void parseErrorHandler(
     final ErrorHandler eh,
     final String errorHandlerPrefix,
     final Properties props,
     final LoggerRepository hierarchy) {
   boolean rootRef =
       OptionConverter.toBoolean(
           OptionConverter.findAndSubst(errorHandlerPrefix + ROOT_REF, props), false);
   if (rootRef) {
     eh.setLogger(hierarchy.getRootLogger());
   }
   String loggerName = OptionConverter.findAndSubst(errorHandlerPrefix + LOGGER_REF, props);
   if (loggerName != null) {
     Logger logger =
         (loggerFactory == null)
             ? hierarchy.getLogger(loggerName)
             : hierarchy.getLogger(loggerName, loggerFactory);
     eh.setLogger(logger);
   }
   String appenderName =
       OptionConverter.findAndSubst(errorHandlerPrefix + APPENDER_REF_TAG, props);
   if (appenderName != null) {
     Appender backup = parseAppender(props, appenderName);
     if (backup != null) {
       eh.setBackupAppender(backup);
     }
   }
 }
 /** Parse non-root elements, such non-root categories and renderers. */
 protected void parseCatsAndRenderers(Properties props, LoggerRepository hierarchy) {
   Enumeration enumeration = props.propertyNames();
   while (enumeration.hasMoreElements()) {
     String key = (String) enumeration.nextElement();
     if (key.startsWith(CATEGORY_PREFIX) || key.startsWith(LOGGER_PREFIX)) {
       String loggerName = null;
       if (key.startsWith(CATEGORY_PREFIX)) {
         loggerName = key.substring(CATEGORY_PREFIX.length());
       } else if (key.startsWith(LOGGER_PREFIX)) {
         loggerName = key.substring(LOGGER_PREFIX.length());
       }
       String value = OptionConverter.findAndSubst(key, props);
       Logger logger = hierarchy.getLogger(loggerName, loggerFactory);
       synchronized (logger) {
         parseCategory(props, logger, key, loggerName, value);
         parseAdditivityForLogger(props, logger, loggerName);
       }
     } else if (key.startsWith(RENDERER_PREFIX)) {
       String renderedClass = key.substring(RENDERER_PREFIX.length());
       String renderingClass = OptionConverter.findAndSubst(key, props);
       if (hierarchy instanceof RendererSupport) {
         RendererMap.addRenderer((RendererSupport) hierarchy, renderedClass, renderingClass);
       }
     } else if (key.equals(THROWABLE_RENDERER_PREFIX)) {
       if (hierarchy instanceof ThrowableRendererSupport) {
         ThrowableRenderer tr =
             (ThrowableRenderer)
                 OptionConverter.instantiateByKey(
                     props,
                     THROWABLE_RENDERER_PREFIX,
                     org.apache.log4j.spi.ThrowableRenderer.class,
                     null);
         if (tr == null) {
           LogLog.error("Could not instantiate throwableRenderer.");
         } else {
           PropertySetter setter = new PropertySetter(tr);
           setter.setProperties(props, THROWABLE_RENDERER_PREFIX + ".");
           ((ThrowableRendererSupport) hierarchy).setThrowableRenderer(tr);
         }
       }
     }
   }
 }