Polish "Enable checkstyle in buildSrc"

See gh-31445

Author: snicoll

buildSrc/config/checkstyle/checkstyle.xml

@@ -1,9 +1,16 @@
 <?xml version="1.0"?>
-<!DOCTYPE module PUBLIC
-		"-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
-		"https://checkstyle.org/dtds/configuration_1_3.dtd">
+<!DOCTYPE module PUBLIC "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN" "https://checkstyle.org/dtds/configuration_1_3.dtd">
 <module name="com.puppycrawl.tools.checkstyle.Checker">
 
+	<!-- Root Checks -->
+	<module name="io.spring.javaformat.checkstyle.check.SpringHeaderCheck">
+		<property name="fileExtensions" value="java"/>
+		<property name="headerType" value="apache2"/>
+		<property name="headerCopyrightPattern" value="20\d\d-20\d\d"/>
+		<property name="packageInfoHeaderType" value="none"/>
+	</module>
+	<module name="com.puppycrawl.tools.checkstyle.checks.NewlineAtEndOfFileCheck"/>
+
 	<!-- TreeWalker Checks -->
 	<module name="com.puppycrawl.tools.checkstyle.TreeWalker">