(Android) Introduce a fix/troubleshooting doc for issues with conflic…

…ting kotlin stdlib flavours

detox/android/detox/build.gradle

@@ -8,7 +8,6 @@ def _compileSdkVersion = _ext.has('compileSdkVersion') ? _ext.compileSdkVersion
 def _buildToolsVersion = _ext.has('buildToolsVersion') ? _ext.buildToolsVersion : '27.0.3'
 def _minSdkVersion = _ext.has('minSdkVersion') ? _ext.minSdkVersion : 18
 def _targetSdkVersion = _ext.has('targetSdkVersion') ? _ext.targetSdkVersion : 25
-def _kotlinVersion = _ext.has('detoxKotlinVersion') ? _ext.detoxKotlinVersion : '1.3.0'
 
 android {
     compileSdkVersion _compileSdkVersion
@@ -58,7 +57,7 @@ android {
 }
 
 dependencies {
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$_kotlinVersion"
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.2.0"
 
     // noinspection GradleDynamicVersion
     compileOnly 'com.facebook.react:react-native:+'

detox/test/android/build.gradle

@@ -1,6 +1,5 @@
 buildscript {
     ext.kotlinVersion = '1.3.0'
-    ext.detoxKotlinVerion = ext.kotlinVersion
     ext.buildToolsVersion = '27.0.3'
 
     repositories {

docs/Introduction.Android.md

@@ -85,7 +85,7 @@ Please be aware that the `minSdkVersion` needs to be at least 18.
 
 ### 3. Add Kotlin
 
-If your project does not already use Kotlin, add the Kotlin Gradle-plugin to your classpath in `android/build.gradle`:
+If your project does not already support Kotlin, add the Kotlin Gradle-plugin to your classpath in the root build-script (i.e.`android/build.gradle`):
 
 ```groovy
 buildscript {
@@ -102,14 +102,6 @@ buildscript {
 _Note: most guides advise of defining a global `kotlinVersion` constant - as in this example, but that is not mandatory._
 
 
-**IMPORTANT:** Detox aims at a playing fair with your app, and so it allows you to explicitly define the kotlin version for it to use - so as to align it with your own; Please do so - in your root `android/build.gradle` configuration file:
-
-```groovy
-buildscript {
-    ext.kotlinVersion = '1.3.0' // Your app's version
-    ext.detoxKotlinVersion = ext.kotlinVersion // Detox' version: should be 1.1.0 or higher!
-}
-```
 
 ***Note that Detox has been tested for version 1.1.0 of Kotlin, and higher!***
 
@@ -207,6 +199,24 @@ packagingOptions {
 
 
 
+### Problem: Kotlin stdlib version conflicts
+
+Of all [Kotlin implementation flavours](https://kotlinlang.org/docs/reference/using-gradle.html#configuring-dependencies), Detox assumes the most recent one, namely `kotlin-stdlib-jdk8`. If your Android build fails due to conflicts with implementations coming from other dependencies or even your own app, consider adding an exclusion to either the "other" dependencies or detox itself, for example:
+
+```diff
+dependencies {
+-    androidTestImplementation('com.wix:detox:+') { transitive = true } 
++    androidTestImplementation('com.wix:detox:+') { 
++        transitive = true
++        exclude group: 'org.jetbrains.kotlin', module: 'kotlin-stdlib-jdk8'
++    }
+}
+```
+
+Detox should work with `kotlin-stdlib-jdk7`, as well.
+
+
+
 ## Setting Detox up as a compiling dependency
 
 This is an **alternative** to the setup process described under the previous section, on adding Detox as a dependency.