Reuse compliance

config/checkstyle/checkstyle.xml

@@ -1,4 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
+<!--
+SPDX-FileCopyrightText: 2021 Paul Schaub <info@pgpainless.org>
+
+SPDX-License-Identifier: CC0-1.0
+-->
+
 <!DOCTYPE module PUBLIC
         "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
         "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
@@ -9,13 +15,6 @@
         <property name="file" value="${config_loc}/suppressions.xml"/>
     </module>
 
-    <!-- License Header -->
-    <module name="Header">
-        <property name="headerFile" value="${config_loc}/checkstyleLicenseHeader.txt"/>
-        <property name="ignoreLines" value="2"/>
-        <property name="fileExtensions" value="java"/>
-    </module>
-
     <module name="NewlineAtEndOfFile">
         <property name="lineSeparator" value="lf"/>
     </module>

config/checkstyle/checkstyleLicenseHeader.txt

@@ -1,15 +0,0 @@
-/*
- * Copyright 2018 Author Authorsson.
- *
- * 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.
- */

config/checkstyle/suppressions.xml

@@ -1,4 +1,10 @@
 <?xml version="1.0"?>
+<!--
+SPDX-FileCopyrightText: 2021 Paul Schaub <info@pgpainless.org>
+
+SPDX-License-Identifier: CC0-1.0
+-->
+
 <!DOCTYPE suppressions PUBLIC
         "-//Puppy Crawl//DTD Suppressions 1.1//EN"
         "http://www.puppycrawl.com/dtds/suppressions_1_1.dtd">