ERROR: Failed to resolve: xxx.xx Add Google Maven repository and sync project

問題描述：

ERROR: Failed to resolve: com.android.support.test.espresso:espresso-core:2.2.2
Add Google Maven repository and sync project

解決：

1. build.gradle

   buildscript {
       repositories {
           jcenter()
           maven {
               url "https://maven.google.com"
           }
       }
       ...
   }
   

或者

2. build.gradle(Project)

   allprojects {
       repositories {
           jcenter()
           maven {
               url "https://maven.google.com"
           }
       }
   }