web-server/doc/en/developer/source/programming-guide/ows-services/hello/pom.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<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>

<!-- set parent pom to community pom -->
<parent>
    <groupId>org.geoserver</groupId>
    <artifactId>community</artifactId>
    <version>2.26-SNAPSHOT</version> <!-- change this to the proper GeoServer version -->
</parent>  

<groupId>org.geoserver</groupId>
<artifactId>hello</artifactId>
<packaging>jar</packaging>
<version>1.0</version>
<name>Hello World Service Module</name>

<!-- declare dependency on geoserver main -->
<dependencies>
    <dependency>
        <groupId>org.geoserver</groupId>
        <artifactId>gs-main</artifactId>
        <version>2.26-SNAPSHOT</version> <!-- change this to the proper GeoServer version -->
    </dependency>
</dependencies>

<repositories>
    <repository>
        <id>boundless</id>
        <name>Boundless Maven Repository</name>
        <url>https://repo.boundlessgeo.com/snapshot</url>
        <snapshots>
            <enabled>true</enabled>
        </snapshots>
    </repository>
</repositories>

</project>