add mandatory style checks to gradle build

build.gradle

@@ -11,6 +11,9 @@ buildscript {
         classpath 'com.getkeepsafe.dexcount:dexcount-gradle-plugin:0.8.3'
     }
 }
+plugins {
+    id 'com.diffplug.gradle.spotless' version '3.14.0'
+}
 
 allprojects {
     repositories {
@@ -31,12 +34,14 @@ ext {
     // regular
     buildTools = "27.0.3"
     compileSdk = 27
-    minSdk = 14
+    minSdk = 16
     targetSdk = 27
 
     sourceCompatibilityVersion = JavaVersion.VERSION_1_8
     targetCompatibilityVersion = JavaVersion.VERSION_1_8
 
+    appOutputFolder = "../../java/com.sap.sailing.www/apps/"
+
     support = "27.1.1"
     play_services = "15.0.1"
 
@@ -49,4 +54,38 @@ ext {
     // testing - ui
     test = "0.2"
     espresso = "2.1"
-}
+}   targetSdk = 27
+
+    isXmakeBuild = project.hasProperty('xmake')
+    isReleaseBuild = Boolean.parseBoolean(System.env.XMAKE_RELEASE_BUILD)
+
+    sourceCompatibilityVersion = JavaVersion.VERSION_1_8
+    targetCompatibilityVersion = JavaVersion.VERSION_1_8
+
+    appOutputFolder = "../../java/com.sap.sailing.www/apps/"
+
+    support = "27.1.1"
+    play_services = "15.0.1"
+
+    license_dialog = "1.8.0"
+
+    // testing - jvm
+    junit = "4.12"
+    mockito = "1.9.5"
+
+    // testing - ui
+    test = "0.2"
+    espresso = "2.1"
+}
+
+spotless {
+    java {
+        importOrder 'java', 'javax', 'org', 'com', ''
+        removeUnusedImports()
+        eclipse().configFile('java/CodeFormatter.xml')
+        target project.fileTree(project.rootDir) {
+            include 'mobile/com.sap.*/**/*.java'
+            exclude '**/generated*/**/*.*', '**/gen/**/*'
+        }
+    }
+}