Use Spotless for license headers

HEADER

@@ -1,13 +1,16 @@
-Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * 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.
+ */
 
-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.

build.gradle

@@ -1,7 +1,7 @@
 plugins {
 	id 'java-library'
 	id 'maven-publish'
-	id 'org.cadixdev.licenser'
+	id 'com.diffplug.spotless'
 	id 'com.github.johnrengelman.shadow'
 	id 'checkstyle'
 }
@@ -47,9 +47,10 @@ dependencies {
 	testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:${junit_jupiter_version}"
 }
 
-license {
-	header project.file('HEADER')
-	include '**/*.java'
+spotless {
+	java {
+		licenseHeaderFile(rootProject.file('HEADER'))
+	}
 }
 
 jar {

gradle.properties

@@ -4,7 +4,7 @@ org.gradle.parallel = true
 org.gradle.workers.max = 3
 
 # Gradle Plugins
-cadixdev_licenser_version = 0.6.1
+spotless_version = 6.13.0
 shadow_version = 7.1.2
 
 # Project Properties

settings.gradle

@@ -4,7 +4,7 @@ pluginManagement {
 		mavenCentral();
 	}
 	plugins {
-		id 'org.cadixdev.licenser' version "${cadixdev_licenser_version}"
+		id 'com.diffplug.spotless' version "${spotless_version}"
 		id 'com.github.johnrengelman.shadow' version "${shadow_version}"
 	}
 }