checkstyle.xml

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
        "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
        "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">

<module name="Checker">
    <property name="charset" value="UTF-8"/>

    <property name="severity" value="error"/>

    <property name="fileExtensions" value="java, properties, xml"/>

    <module name="TreeWalker">
        <module name="RegexpSinglelineJava">
            <property name="format" value="^\t* "/>
            <property name="message" value="Indent must use tab characters"/>
            <property name="ignoreComments" value="true"/>
        </module>

        <module name="WhitespaceAround">
            <property name="tokens" value="LCURLY,RCURLY,COLON"/>
            <property name="allowEmptyMethods" value="true" />
            <property name="allowEmptyConstructors" value="true" />
            <property name="ignoreEnhancedForColon" value="false" />
        </module>

        <module name="NeedBraces"/>
    </module>
</module>