安装doc api出问题了 [ 2.0 版本 ]

composer require --prefer-dist yiisoft/yii2-apidoc

错误如下：

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Can only install one of: phpdocumentor/reflection-docblock[2.0.4, 3.1.1].
    - Can only install one of: phpdocumentor/reflection-docblock[3.1.1, 2.0.4].
    - Can only install one of: phpdocumentor/reflection-docblock[2.0.4, 3.1.1].
    - yiisoft/yii2-apidoc 2.1.0 requires phpdocumentor/reflection-docblock ^2.0.4 -> satisfiable by phpdocumentor/reflection-docblock[2.0.4].
    - Installation request for yiisoft/yii2-apidoc ^2.1 -> satisfiable by yiisoft/yii2-apidoc[2.1.0].
    - Installation request for phpdocumentor/reflection-docblock == 3.1.1.0 -> satisfiable by phpdocumentor/reflection-docblock[3.1.1].