Prepare project for Kotlin migration (#1257)

adapters/build.gradle.kts

@@ -15,8 +15,9 @@
  */
 
 plugins {
-  `java-library`
+  kotlin("jvm")
   id("com.vanniktech.maven.publish")
+  id("ru.vyarus.animalsniffer")
 }
 
 dependencies {

adapters/japicmp/build.gradle.kts

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2020 Square, Inc.
+ *
+ * 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
+ *
+ *    https://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.
+ */
+
+import me.champeau.gradle.japicmp.JapicmpTask
+
+plugins {
+  `java-library`
+  id("me.champeau.gradle.japicmp")
+}
+
+val baseline = configurations.create("baseline")
+val latest = configurations.create("latest")
+
+dependencies {
+  baseline("com.squareup.moshi:moshi-adapters:1.11.0") {
+    isTransitive = false
+    isForce = true
+  }
+  latest(project(":adapters"))
+}
+
+val japicmp = tasks.register<JapicmpTask>("japicmp") {
+  dependsOn("jar")
+  oldClasspath = baseline
+  newClasspath = latest
+  onlyBinaryIncompatibleModified = true
+  failOnModification = true
+  txtOutputFile = file("$buildDir/reports/japi.txt")
+  ignoreMissingClasses = true
+  includeSynthetic = true
+}
+
+tasks.named("check").configure {
+  dependsOn(japicmp)
+}