For API 23:
Top level build.gradle – /build.gradle
buildscript {
...
dependencies {
classpath 'com.android.tools.build:gradle:1.3.1'
}
}
...
Module specific build.gradle – /app/build.gradle
android {
compileSdkVersion 23
buildToolsVersion "23.0.0"
useLibrary 'org.apache.http.legacy'
...
}
Official docs (for preview though): http://developer.android.com/about/versions/marshmallow/android-6.0-changes.html#behavior-apache-http-client
Latest android gradle plugin changelog: http://tools.android.com/tech-docs/new-build-system