Buidle Gradle - Root and App

app buidle.gradle

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.neenbedankt.gradle.plugins:android-apt:1.4'
    }
}

repositories {
    mavenCentral()
    mavenLocal()
}

apply plugin: 'com.android.application'
apply plugin: 'android-apt'
def AAVersion = '3.1'

dependencies {
    compile 'com.android.support:appcompat-v7:21.0.0'
    apt "org.androidannotations:androidannotations:$AAVersion"
    compile "org.androidannotations:androidannotations:$AAVersion"
}

apt {
    arguments {
        androidManifestFile variant.outputs[0].processResources.manifestFile
        resourcePackageName 'your complete manifest package name'
    }
}

android {
    compileSdkVersion 21 (Important!)
    buildToolsVersion '20.0.0' (Important!)

    defaultConfig {
        minSdkVersion 11 
        targetSdkVersion 21
    }

    sourceSets {
        main {
            manifest.srcFile 'src/main/AndroidManifest.xml'
            java.srcDirs = ['src/main/java', 'build/generated/source/apt/${variant.dirName}']
            resources.srcDirs = ['src/main/res']
            res.srcDirs = ['src/main/res']
            assets.srcDirs = ['assets']
        }
    }

    packagingOptions {
        exclude 'META-INF/DEPENDENCIES.txt'
        exclude 'META-INF/LICENSE.txt'
        exclude 'META-INF/NOTICE.txt'
        exclude 'META-INF/NOTICE'
        exclude 'META-INF/LICENSE'
        exclude 'META-INF/DEPENDENCIES'
        exclude 'META-INF/notice.txt'
        exclude 'META-INF/license.txt'
        exclude 'META-INF/dependencies.txt'
        exclude 'META-INF/LGPL2.1'
    }
}

root.build.gradle

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:1.0.0'
    }
}

allprojects {
    repositories {
        mavenCentral()
    }
}

How about the:
"Error: Could not find property 'processResources' on com.android.build.gradle.internal.api.ApplicationVariantImpl_Decorated@48f217d0."
that points to:
"androidManifestFile variant.processResources.manifestFile" ?

change:
androidManifestFile variant.processResources.manifestFile

to:
androidManifestFile variant.outputs[0].processResources.manifestFile