Re-org before joining repositories again (#2241)

gradle/animalsniffer.gradle

@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2021 The Arrow Authors
+ *
+ * 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.
+ */
+
+// -- Gradle Animal Sniffer Plugin: https://github.com/xvik/gradle-animalsniffer-plugin
+apply plugin: 'ru.vyarus.animalsniffer'
+apply plugin: 'java'
+animalsniffer {
+    sourceSets = [sourceSets.main] // Ingore tests
+    ignore 'java.lang.*'
+}
+dependencies {
+    compileOnly "org.codehaus.mojo:animal-sniffer-annotations:1.19"
+    signature 'net.sf.androidscents.signature:android-api-level-21:5.0.1_r2@signature'
+}