Polish "Use kotlin_module not kotlin-module to identify Kotlin module metadata"

See gh-16004

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/it/jar-with-kotlin-module/src/main/kotlin/org/test/SampleApplication.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/it/jar-with-kotlin-module/verify.groovy

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.