src/it/projects/basic-features/ExecutionRoot/pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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>
  <parent>
    <groupId>org.apache.maven.plugin.assembly.test</groupId>
    <artifactId>it-project-parent</artifactId>
    <version>1</version>
  </parent>
  
  <groupId>org.test</groupId>
  <artifactId>parent</artifactId>
  <version>1.0</version>
  <packaging>pom</packaging>
  
  <name>Parent</name>
  <modules>
    <module>child</module>
  </modules>
  <dependencies>
    <dependency>
      <groupId>commons-logging</groupId>
      <artifactId>commons-logging</artifactId>
      <version>1.0.4</version>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-assembly-plugin</artifactId>
        <configuration>
          <runOnlyAtExecutionRoot>true</runOnlyAtExecutionRoot>
          <descriptorRefs>
            <descriptorRef>project</descriptorRef>
          </descriptorRefs>
        </configuration>
        <executions>
          <execution>
            <goals>
              <goal>single</goal>
            </goals>
            <phase>validate</phase>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>