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">
  <!-- See http://checkstyle.sourceforge.net/config_whitespace.html -->
  <module name="FileTabCharacter"/>

  <!-- See http://checkstyle.sourceforge.net/config_misc.html -->
  <module name="RegexpSingleline">
    <property name="format" value="\s+$"/>
    <property name="minimum" value="0"/>
    <property name="maximum" value="0"/>
    <property name="message" value="Line has trailing spaces."/>
  </module>

  <module name="TreeWalker">
    <!-- See http://checkstyle.sourceforge.net/config_filters.html -->
    <module name="SuppressionCommentFilter"/>

    <!-- See http://checkstyle.sourceforge.net/config_imports.html -->
    <module name="RedundantImport"/>
    <module name="UnusedImports"/>

    <!-- See http://checkstyle.sourceforge.net/config_modifiers.html -->
    <module name="ModifierOrder"/>

    <!-- See http://checkstyle.sourceforge.net/config_design.html -->
    <module name="FinalClass"/>

    <!-- See http://checkstyle.sourceforge.net/config_misc.html -->
    <module name="ArrayTypeStyle"/>
    <module name="UpperEll"/>
  </module>
</module>