src/it/multi-modules-aggregate/pom.xml

<?xml version="1.0" encoding="UTF-8"?>
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  ~ 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
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  ~   http://www.apache.org/licenses/LICENSE-2.0
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>org.apache.maven.plugins.checkstyle.its</groupId>
  <artifactId>multi-modules-aggregate-parent</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>pom</packaging>
  <name>multi-modules-parent</name>
  <url>http://maven.apache.org/</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <build>
    <pluginManagement>
      <plugins>
        <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-checkstyle-plugin</artifactId>
          <version>@pom.version@</version>
        </plugin>
      </plugins>
    </pluginManagement>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-site-plugin</artifactId>
        <version>@sitePluginVersion@</version>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-checkstyle-plugin</artifactId>
        <version>@pom.version@</version>
      </plugin>
    </plugins>
  </build>

  <reporting>
    <excludeDefaults>true</excludeDefaults>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-checkstyle-plugin</artifactId>
        <version>@pom.version@</version>
        <configuration>
          <!-- this is the file we had in 2.13, slightly adapted to Checkstyle 8.x -->
          <configLocation>maven_checks.xml</configLocation>
          <includeTestSourceDirectory>true</includeTestSourceDirectory>
        </configuration>
        <inherited>false</inherited>
        <reportSets>
          <reportSet>
            <reports>
              <report>checkstyle-aggregate</report>
            </reports>
          </reportSet>
        </reportSets>
      </plugin>
    </plugins>
  </reporting>
  <modules>
    <module>child-a</module>
    <module>child-b</module>
    </modules>
</project>