code: @Override
      public boolean modelPrimaryKeyClassGenerated(TopLevelClass topLevelClass, IntrospectedTable introspectedTable) {
          this.generateModelEnum(topLevelClass, introspectedTable);
          return super.modelPrimaryKeyClassGenerated(topLevelClass, introspectedTable);
      }
docs: 具体执行顺序 http://www.mybatis.org/generator/reference/pluggingIn.html
  @param topLevelClass
  @param introspectedTable
  @return