Conflict with dependency 'com.android.support:support-annotations' in project ':app'. Resolved versions for app (26.1.0) and test app

  에러 내용

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.

해결 : 

dependencies {

    implementation fileTree(dir: 'libs', include: ['*.jar'])

    implementation 'com.android.support:appcompat-v7:26.1.0'

    implementation 'com.android.support.constraint:constraint-layout:1.1.0'

    testImplementation 'junit:junit:4.12'

    androidTestImplementation 'com.android.support.test:runner:1.0.2'

    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'

    compile 'com.android.support:support-annotations:27.1.1' <<를 추가해 준다.

}

출처: http://stage-diary.tistory.com/232 [꽃이 흘러 내리는 나만의 스테이지]