checkstyle.xml

<?xml version="1.0"?>

<!DOCTYPE module PUBLIC
    "-//Puppy Crawl//DTD Check Configuration 1.1//EN"
    "http://www.puppycrawl.com/dtds/configuration_1_1.dtd">

<!-- commons digester customization of default Checkstyle behavior -->
<module name="Checker">
  <property name="localeLanguage" value="en"/>

  <module name="TreeWalker">
    <!-- Verify that EVERY source file has the appropriate license -->
    <module name="Header">
      <property name="headerFile" value="file-header.txt"/>
      <property name="ignoreLines" value="1,3"/>
    </module>

    <!-- no tabs allowed in files -->
    <module name="TabCharacter"/>
    
    <!-- check sane import statements -->
    <module name="AvoidStarImport"/>
    <module name="RedundantImport"/>
    <module name="UnusedImports"/>

    <module name="LineLength">
      <property name="max" value="120"/>
    </module>
  </module>
</module>