code: @Override
      public void removeAppender(Appender appender) {
          if (appender == null || appenderList == null)
              return;
          appenderList.remove(appender);
          configuredAppenderList.remove(appender.getName());
      }
docs: /*
  (non-Javadoc)
  
  @see
  org.apache.log4j.helpers.AppenderAttachableImpl#removeAppender(org.apache
  .log4j.Appender)