Simple-File-Manager/app/build.gradle

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.2"

    defaultConfig {
        applicationId "com.simplemobiletools.filemanager"
        minSdkVersion 16
        targetSdkVersion 23
        versionCode 28
        versionName "2.1.0"
    }

    signingConfigs {
        release
    }

    buildTypes {
        release {
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
            signingConfig signingConfigs.release
        }
    }

    sourceSets {
        main.java.srcDirs += 'src/main/kotlin'
    }
}

dependencies {
    compile 'com.simplemobiletools:commons:2.13.5'
    compile 'com.bignerdranch.android:recyclerview-multiselect:0.2'
    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
}

buildscript {
    ext.kotlin_version = '1.1.1'
    repositories {
        mavenCentral()
    }

    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"
    }
}

def Properties props = new Properties()
def propFile = new File('signing.properties')
if (propFile.canRead()) {
    props.load(new FileInputStream(propFile))

    if (props != null && props.containsKey('STORE_FILE') && props.containsKey('KEY_ALIAS') && props.containsKey('PASSWORD')) {
        android.signingConfigs.release.storeFile = file(props['STORE_FILE'])
        android.signingConfigs.release.storePassword = props['PASSWORD']
        android.signingConfigs.release.keyAlias = props['KEY_ALIAS']
        android.signingConfigs.release.keyPassword = props['PASSWORD']
    } else {
        println 'signing.properties found but some entries are missing'
        android.buildTypes.release.signingConfig = null
    }
} else {
    println 'signing.properties not found'
    android.buildTypes.release.signingConfig = null
}