WorldGuard/worldguard-legacy/config/checkstyle/checkstyle.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE module PUBLIC
    "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
    "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
<module name="Checker">
  <!-- Tabs are strictly banned -->
  <module name="FileTabCharacter"/>

  <module name="TreeWalker">
    <!-- Important basics -->
    <!-- <module name="PackageDeclaration"/> Unlikely that we would miss this in a PR -->
    <module name="OuterTypeFilename"/> <!-- TypeName -> TypeName.java -->

    <!--
    Control package usage, so people don't insert Bukkit into WE where it shouldn't belong, etc.
    It is a bit draconian, so update as necessary!
    -->
    <module name="ImportControl">
      <property name="file" value="worldguard-legacy/config/checkstyle/import-control.xml"/>
    </module>

    <!-- Code -->
    <module name="HideUtilityClassConstructor"/> <!-- Utility classes should not have a constructor -->
    <module name="CovariantEquals"/>
    <module name="EqualsHashCode"/> <!-- equals() and hashCode() go together -->
    <module name="NestedTryDepth"> <!-- SHOULD not need to adjust this -->
      <property name="max" value="2"/>
    </module>
    <module name="SuperFinalize"/> <!-- We don't actually use this -->

    <!-- Style -->
    <module name="LeftCurly"> <!-- Left brace never goes on another line -->
      <property name="option" value="eol"/>
    </module> <!-- We don't check right brace -->
    <module name="DefaultComesLast"/> <!-- default case in switch should be last -->
    <module name="GenericWhitespace"/>

    <!-- Naming -->
    <module name="ClassTypeParameterName">
      <property name="format" value="^[A-Z][a-zA-Z0-9]*$"/>
    </module>
    <module name="LocalFinalVariableName"/>
    <module name="LocalVariableName">
      <property name="format" value="^[a-z_][a-zA-Z0-9]*$"/>
    </module>
    <module name="MemberName">
      <property name="format" value="^[a-z_][a-zA-Z0-9]*$"/>
    </module>
    <module name="MethodName">
      <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
    </module>
    <!-- <module name="PackageName"/> Unlikely that we would miss this in a PR -->
    <module name="ParameterName"/>
    <!-- <module name="TypeName"/> Unlikely that we would miss this in a PR -->
  </module>

  <!-- Require the header, something that many people forget and we hate to fix -->
  <!-- You should configure the header in your IDE -->
  <module name="Header">
    <property name="headerFile" value="config/checkstyle/header.txt"/>
    <property name="fileExtensions" value="java"/>
  </module>
</module>