ChestCommands/checkstyle/checkstyle.xml

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
        "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
        "https://checkstyle.org/dtds/configuration_1_3.dtd">

<module name="Checker">
    <property name="fileExtensions" value="java, xml"/>
    <property name="charset" value="UTF-8"/>

    <module name="SuppressionFilter">
        <property name="file" value="checkstyle/suppressions.xml"/>
    </module>

    <!-- Check that Java source files have the correct header -->
    <module name="Header">
        <property name="fileExtensions" value="java"/>
        <property name="headerFile" value="checkstyle/header.txt"/>
    </module>
</module>