private AST createFromElement(String text) {
   AST ast =
       ASTUtil.create(
           fromClause.getASTFactory(),
           implied
               ? IMPLIED_FROM
               : FROM_FRAGMENT, // This causes the factory to instantiate the desired class.
           text);
   // Reset the node type, because the rest of the system is expecting FROM_FRAGMENT, all we wanted
   // was
   // for the factory to create the right sub-class.  This might get reset again later on anyway to
   // make the
   // SQL generation simpler.
   ast.setType(FROM_FRAGMENT);
   return ast;
 }