Conflict with dependency 'com.an

有时候项目编译的时候回报如下的错，虽然不影响运行但是看着难受！

   Conflict with dependency 'com.android.support:support-annotations' in project ':app'. Resolved versions for app (26.1.0) and test app (27.1.1) differ. 
    * What went wrong:
    Execution failed for task ':app:preDebugAndroidTestBuild'.> Conflict with dependency 'com.android.support:support-annotations' in project ':app'. Resolved versions for app (26.1.0) and test app (27.1.1) differ. 

解决方案：

添加依赖
implementation 'com.android.support:support-annotations:27.1.1'