Add check header rule and fixHeaders task

Add "new line" in the header end

* Optimization for the `fixHeaders.gradle`
* Apply the `fixHeaders` for the affected classes

src/checkstyle/checkstyle-header.txt

@@ -1,5 +1,5 @@
 ^\Q/*\E$
-^\Q * Copyright \E20\d\d\-20\d\d\Q the original author or authors.\E$
+^\Q * Copyright \E20\d\d(\-20\d\d)?\Q the original author or authors.\E$
 ^\Q *\E$
 ^\Q * Licensed under the Apache License, Version 2.0 (the "License");\E$
 ^\Q * you may not use this file except in compliance with the License.\E$

src/checkstyle/checkstyle-suppressions.xml

@@ -3,4 +3,5 @@
     "-//Puppy Crawl//DTD Suppressions 1.1//EN"
     "http://www.puppycrawl.com/dtds/suppressions_1_1.dtd">
 <suppressions>
+	<suppress files="package-info\.java" checks=".*" />
 </suppressions>

src/checkstyle/checkstyle.xml

@@ -2,11 +2,16 @@
 <!DOCTYPE module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.2//EN" "http://www.puppycrawl.com/dtds/configuration_1_2.dtd">
 <module name="Checker">
 
+	<module name="SuppressionFilter">
+		<property name="file" value="src/checkstyle/checkstyle-suppressions.xml" />
+	</module>
+
 	<!-- Root Checks -->
-<!-- 	<module name="RegexpHeader"> -->
-<!-- 		<property name="headerFile" value="${checkstyle.header.file}" /> -->
-<!-- 		<property name="fileExtensions" value="java" /> -->
-<!-- 	</module> -->
+ 	<module name="RegexpHeader">
+ 		<property name="headerFile" value="src/checkstyle/checkstyle-header.txt" />
+ 		<property name="fileExtensions" value="java" />
+ 	</module>
+
 	<module name="NewlineAtEndOfFile">
 		<property name="lineSeparator" value="lf"/>
 	</module>

src/checkstyle/fixHeaders.gradle

@@ -0,0 +1,43 @@
+ext {
+	headerTemplate = new File('src/checkstyle/checkstyle-header.txt')
+			.text
+			.replaceAll(/\^\\Q|\\E\$|\^\$|\^\.\*\$/, '')
+			.replaceFirst(/\\E20\\d\\d\(\\-20\\d\\d\)\?\\Q/, '{year}')
+			.trim() + System.lineSeparator()  + System.lineSeparator()
+
+
+	now = Calendar.instance.get(Calendar.YEAR) as String
+}
+
+task fixHeaders << {
+	fileTree("${buildDir}/reports/checkstyle").include('*.xml').each { report ->
+		def xml = new XmlParser(false, false).parse(report)
+		xml.file.each {
+			if (it.error.@source == ['com.puppycrawl.tools.checkstyle.checks.header.RegexpHeaderCheck']) {
+				def years = now
+				def file = new File(it.@name)
+				def line
+				file.withReader { reader ->
+					while (line = reader.readLine()) {
+						def matcher = line =~ /Copyright (20\d\d)(?:-20\d\d)?/
+						if (matcher.count) {
+							years = matcher[0][1]
+							if (years != now) {
+								years = years + "-$now"
+							}
+							break
+						}
+					}
+				}
+
+				def header = headerTemplate.replaceFirst(/\{year}/, years)
+
+				def sourceCode = file.text
+				sourceCode = sourceCode.replaceFirst(/(?s)(?:.*)(package org\.springframework\.integration.*)/,
+						"${header}\$1")
+				file.write(sourceCode)
+				println "Header fixed for $file"
+			}
+		}
+	}
+}