code: public static Expression in(String field, String operator, Val<Expression>[] args, EbeanExprInvoker invoker) {
          if (args.length == 1) {
              if (args[0].object() instanceof QueryExpression) {
                  return factory(invoker).in(field, ((QueryExpression<?>) args[0].object()).query);
              }
              throw new QuerySyntaxException(Messages.get("dsl.arguments.error3", operator));
          }
          return factory(invoker).in(field, args);
      }
docs: <p>in.</p>
  
  @param field a {@link java.lang.String} object.
  @param operator a {@link java.lang.String} object.
  @param args an array of {@link ameba.db.dsl.QueryExprMeta.Val} objects.
  @param invoker a {@link ameba.db.ebean.filter.EbeanExprInvoker} object.
  @return a {@link io.ebean.Expression} object.