sample-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/xsd/maven-4.0.0.xsd"
>
    <modelVersion>4.0.0</modelVersion>
    <groupId>your.group.id</groupId>
    <artifactId>your.artifact.id</artifactId>
    <version>your.version</version>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-enforcer-plugin</artifactId>
                <version>1.2</version>
                <dependencies>
                    <dependency>
                        <groupId>au.net.coldeq</groupId>
                        <artifactId>maven-enforcer-duplicate-class-check</artifactId>
                        <version>1.0</version>
                    </dependency>
                </dependencies>
                <executions>
                    <execution>
                        <id>enforce</id>
                        <configuration>
                            <rules>
                                <myCustomRule implementation="au.net.coldeq.enforcer.BanDuplicateClasses"/>
                            </rules>
                        </configuration>
                        <goals>
                            <goal>enforce</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>