Example of an Androi library module Gradle file

build.gradle

apply plugin: 'com.android.library'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-kapt'

android {
    compileSdkVersion rootProject.ext.compileSdkVersion
    buildToolsVersion rootProject.ext.buidToolsVersion
    defaultConfig {
        minSdkVersion rootProject.ext.minSdkVersion
        targetSdkVersion rootProject.ext.targetSdkVersion
    }

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

    compileOptions {
        targetCompatibility 1.8
        sourceCompatibility 1.8
    }
}

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"

    implementation project(':core')
    compileOnly 'com.google.code.gson:gson:2.8.2'

    compileOnly 'com.jakewharton.timber:timber:4.6.0'
    compileOnly "com.android.support:support-annotations:$playVersion"

    compileOnly "io.reactivex:rxandroid:$rxAndroidVersion"
    compileOnly "io.reactivex:rxjava:$rxJavaVersion"
    compileOnly 'com.jakewharton.rxrelay:rxrelay:1.2.0'
    compileOnly 'com.artemzin.rxjava:proguard-rules:1.3.0.0'
    compileOnly 'nl.littlerobots.rxlint:rxlint:1.6'
    compileOnly 'io.reactivex:rxkotlin:2.0.0-RC1'
}