@Override
 public String escapeColumnNameList(final String columnNames) {
   StringBuffer sb = new StringBuffer();
   for (String columnName : columnNames.split(",")) {
     if (sb.length() > 0) {
       sb.append(", ");
     }
     sb.append(escapeObjectName(columnName.trim(), Column.class));
   }
   return sb.toString();
 }