Harmonize checkstyle configuration

Closes gh-50921

buildSrc/config/checkstyle/checkstyle.xml

@@ -5,13 +5,13 @@
 <module name="com.puppycrawl.tools.checkstyle.Checker">
 	<module name="io.spring.javaformat.checkstyle.SpringChecks">
 		<property name="excludes" value="com.puppycrawl.tools.checkstyle.checks.javadoc.JavadocPackageCheck" />
-		<property name="headerFile" value="${config_loc}/checkstyle-header.txt"/>
+		<property name="headerFile" value="${config_loc}/checkstyle-header.txt" />
 	</module>
 	<module name="com.puppycrawl.tools.checkstyle.TreeWalker">
 		<module name="com.puppycrawl.tools.checkstyle.checks.imports.IllegalImportCheck">
 			<property name="regexp" value="true" />
 			<property name="illegalPkgs"
-				value="^com\.fasterxml\.jackson(?!\.annotation).*" />
+			          value="^com\.fasterxml\.jackson(?!\.annotation).*" />
 		</module>
 	</module>
 </module>

gradle/plugins/config/checkstyle/checkstyle-header.txt

@@ -0,0 +1,15 @@
+/*
+ * Copyright 2012-present 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.
+ * 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.
+ */

gradle/plugins/config/checkstyle/checkstyle.xml

@@ -5,5 +5,6 @@
 <module name="com.puppycrawl.tools.checkstyle.Checker">
 	<module name="io.spring.javaformat.checkstyle.SpringChecks">
 		<property name="excludes" value="com.puppycrawl.tools.checkstyle.checks.javadoc.JavadocPackageCheck" />
+		<property name="headerFile" value="${config_loc}/checkstyle-header.txt" />
 	</module>
 </module>