checkstyle.xml

<?xml version="1.0"?>
<!--
  ~ Licensed to the Apache Software Foundation (ASF) under one
  ~ or more contributor license agreements.  See the NOTICE file
  ~ distributed with this work for additional information
  ~ regarding copyright ownership.  The ASF licenses this file
  ~ to you under the Apache License, Version 2.0 (the
  ~ "License"); you may not use this file except in compliance
  ~ with the License.  You may obtain a copy of the License at
  ~
  ~    http://www.apache.org/licenses/LICENSE-2.0
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  ~ Unless required by applicable law or agreed to in writing,
  ~ software distributed under the License is distributed on an
  ~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  ~ KIND, either express or implied.  See the License for the
  ~ specific language governing permissions and limitations
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  -->     
<!DOCTYPE module PUBLIC
    "-//Puppy Crawl//DTD Check Configuration 1.1//EN"
    "http://www.puppycrawl.com/dtds/configuration_1_1.dtd">

<!-- commons proxy 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="license-header.txt"/>
    </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>