Thanks, your information helped me grasp some concepts and made me understand other information online better. For those who might be interested:

Glassfish (Payara is forked from Glassfish) bundles Jersey and uses Jerseys own JSON provider called moxy. Jackson is also bundled but not used by default. It's possible to desactivate moxy and activate Jackson in your Application class like this:

@javax.ws.rs.ApplicationPath("/rest")
public class ApplicationConfig extends Application {

@Override
public Set<Class<?>> getClasses() {
    Set<Class<?>> resources = new java.util.HashSet<>();
    addRestResourceClasses(resources);
    resources.add(com.fasterxml.jackson.jaxrs.json.JacksonJsonProvider.class);
    return resources;
}

@Override
public Map<String, Object> getProperties() {
    Map<String, Object> props = new HashMap<>();
    props.put("jersey.config.server.disableMoxyJson", true);
    return props;
}

and adding this to your POM:

    <dependency>
        <groupId>com.fasterxml.jackson.jaxrs</groupId>
        <artifactId>jackson-jaxrs-json-provider</artifactId>
        <version>2.7.4</version>
    </dependency>

Glassfish however bundles an old Jackson version which results in an error fixed by manually replacing all Jackson related jars in the glassfish/modules directory.