add kotlin dependency to uhabits-core

android/uhabits-core/build.gradle

@@ -1,4 +1,5 @@
 apply plugin: 'idea'
+apply plugin: 'kotlin'
 apply plugin: 'java'
 apply plugin: 'jacoco'
 
@@ -27,6 +28,7 @@ dependencies {
     implementation('com.opencsv:opencsv:3.9') {
         exclude group: 'commons-logging', module: 'commons-logging'
     }
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$KOTLIN_VERSION"
 }
 
 jacocoTestReport {
@@ -46,3 +48,25 @@ check.dependsOn jacocoTestReport
 
 sourceCompatibility = "1.8"
 targetCompatibility = "1.8"
+
+buildscript {
+    repositories {
+        mavenCentral()
+    }
+    dependencies {
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$KOTLIN_VERSION"
+    }
+}
+repositories {
+    mavenCentral()
+}
+compileKotlin {
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+}
+compileTestKotlin {
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+}