docs: public String selectOne(MappedStatement ms) {
          Class<?> entityClass = getEntityClass(ms);
          //修改返回值类型为实体类型
          setResultType(ms, entityClass);
          StringBuilder sql = new StringBuilder();
          sql.append(SqlHelper.selectAllColumns(entityClass));
          sql.append(SqlHelper.fromTable(entityClass, tableName(entityClass)));
          sql.append(SqlHelper.whereAllIfColumns(entityClass, isNotEmpty()));
          return sql.toString();
      }