Smack/config/checkstyle.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE module PUBLIC
    "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
     "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
<module name="Checker">
	<module name="SuppressionFilter">
		<property name="file" value="config/suppressions.xml"/>
	</module>
	<module name="SuppressionCommentFilter"/>
	<module name="Header">
		<property name="headerFile" value="config/header.txt"/>
		<property name="ignoreLines" value="3"/>
		<property name="fileExtensions" value="java"/>
	</module>
	<module name="NewlineAtEndOfFile">
		<property name="lineSeparator" value="lf"/>
	</module>
	<module name="RegexpSingleline">
		<property name="format" value="MXParser"/>
		<property name="message" value="Must not use MXParser, use XmlPullParserFactory instead"/>
	</module>
	<module name="RegexpSingleline">
		<property name="format" value="^\s+$"/>
		<property name="message" value="Line containing only whitespace character(s)"/>
	</module>
	<module name="RegexpSingleline">
		<property name="format" value="^ +\t+"/>
		<property name="message" value="Line containing tab(s) after space"/>
	</module>
	<module name="RegexpSingleline">
		<!--
			Explaining the following Regex

			^   \s*   [\S && [^  \*/]]+   \s+   $
			|    |        |           |    |    +- End of Line (6)
			|    |        |           |    +- At least one whitespace (5)
			|    |        |           +- At least one or more of the previous character class (4)
			|    |        +- All non-whitespace characters except '*' and '/' (to exclude javadoc) (3)
			|    +- Zero or more space characters (2)
			+- Start of Line (1)

			Rationale:
			Matches trailing whitespace (5) in lines containing at least one (4) non-whitespace character
			that is not one of the characters used by javadoc (3).
		-->
		<property name="format" value="^\s*[\S&amp;&amp;[^\*/]]+\s+$"/>
		<property name="message" value="Line containing trailing whitespace character(s)"/>
	</module>
	<module name="TreeWalker">
		<module name="FileContentsHolder"/>
		<module name="UnusedImports">
			<property name="processJavadoc" value="true"/>
		</module>
		<module name="AvoidStarImport"/>
		<module name="IllegalImport"/>
		<module name="RedundantImport"/>
		<module name="UpperEll"/>
		<module name="ArrayTypeStyle"/>
		<module name="GenericWhitespace"/>
		<module name="EmptyStatement"/>
		<module name="PackageDeclaration"/>
		<module name="RegexpSinglelineJava">
			<property name="format" value="printStackTrace"/>
			<property name="message" value="Usage of printStackTrace"/>
			<property name="ignoreComments" value="true"/>
		</module>
		<module name="RegexpSinglelineJava">
			<property name="format" value="println"/>
			<property name="message" value="Usage of println"/>
			<property name="ignoreComments" value="true"/>
		</module>
	</module>
</module>