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="CustomImportOrder">
            <property name="customImportOrderRules"
                      value="THIRD_PARTY_PACKAGE###SPECIAL_IMPORTS###STANDARD_JAVA_PACKAGE###STATIC"/>
            <property name="specialImportsRegExp" value="^javax\."/>
            <property name="standardPackageRegExp" value="^java\."/>
            <property name="sortImportsInGroupAlphabetically" value="true"/>
            <property name="separateLineBetweenGroups" value="true"/>
        </module>
        <module name="UnusedImports"/>
        <module name="RedundantImport"/>
    </module>
</module>