added spotless plugin & dependency

Author: Developerarif2

build.gradle

@@ -1,5 +1,3 @@
-// Top-level build file where you can add configuration options common to all sub-projects/modules.
-
 buildscript {
     ext {
         kotlin_version = '1.2.71'
@@ -20,6 +18,7 @@ buildscript {
     dependencies {
         classpath "com.android.tools.build:gradle:3.2.1"
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+        classpath "com.diffplug.spotless:spotless-plugin-gradle:3.16.0"
         classpath "com.novoda:bintray-release:0.9"
     }
 }

spotless.gradle

@@ -0,0 +1,17 @@
+apply plugin: "com.diffplug.gradle.spotless"
+spotless {
+    java {
+        target "**/*.java"
+        trimTrailingWhitespace()
+        removeUnusedImports()
+        googleJavaFormat('1.6').aosp()
+        endWithNewline()
+    }
+    kotlin {
+        target "**/*.kt"
+        ktlint().userData(['indent_size': '4', 'continuation_indent_size': '4'])
+        licenseHeaderFile '../spotless.license.kt'
+        trimTrailingWhitespace()
+        endWithNewline()
+    }
+}

spotless.license.kt

@@ -0,0 +1,16 @@
+/*
+ * Copyright (C) 2018 skydoves
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+