java-tutorials/maven-polyglot/maven-polyglot-json-app/.mvn/extensions.xml

<?xml version="1.0" encoding="UTF-8"?>
<extensions>
    <extension>
        <groupId>com.baeldung.maven.polyglot</groupId>
        <artifactId>maven-polyglot-json-extension</artifactId>
        <version>1.0-SNAPSHOT</version>
    </extension>
</extensions>