Add multidex keep file support in the build.gradle

build.gradle.gist

android.applicationVariants.all { variant ->
    task "fix${variant.name.capitalize()}MainDexClassList" << {
        logger.info "Fixing main dex keep file for $variant.name"
        File keepFile = new File("$buildDir/intermediates/multi-dex/$variant.buildType.name/maindexlist.txt")
        keepFile.withWriterAppend { w ->
            // Get a reader for the input file
            w.append('\n')
            new File("${projectDir}/multidex.keep").withReader { r ->
                // And write data from the input into the output
                w << r << '\n'
            }
            logger.info "Updated main dex keep file for ${keepFile.getAbsolutePath()}\n$keepFile.text"
        }
    }
}
tasks.whenTaskAdded { task ->
    android.applicationVariants.all { variant ->
        if (task.name == "create${variant.name.capitalize()}MainDexClassList") {
            task.finalizedBy "fix${variant.name.capitalize()}MainDexClassList"
        }
    }
}