Extract mapping gradle task

extract_mapping.gradle

def extractMapping = tasks.create("extractMapping") {
    description "Copy mapping archive into outputs/artifacts folder."
    group 'circleci'
}

android.applicationVariants.all { variant ->
    if (variant.mappingFile != null) {
        def copyMapping = tasks.create(name: "copy${variant.name}Mapping", type: Copy) {
            from variant.mappingFile
            rename { "${archivesBaseName}-${variant.name}Mapping.txt" }
            into "${rootProject.buildDir}/circleci/mapping"
        }
        extractMapping.dependsOn copyMapping
    }
}