code: @Override
      public boolean isAttached(Appender appender) {
          if (appender == null || aai == null)
              return false;
          else {
              return aai.isAttached(appender);
          }
      }
docs: /*
  (non-Javadoc)
  
  @see org.apache.log4j.Category#isAttached(org.apache.log4j.Appender)