Jersey 2 InjectLink is ignored - json

Question

I'm creating a new Jersey 2.21, Jackson 2.6.1 REST server (I tried with Jersey 2.19 and Jackson 2.5.3 as well) and a want to use #InjectLink to provide HATEOAS links (like 'self') for my callers. The most basic app (taken from Jersey doc and Jersey sample apps) isn't working, and I can't figure out why.
I started by taking the basic Widgets class from the Jersey doc, but the JSON or XML returned is just an empty structure.
XML:
<Widgets/>
JSON:
{}
Widgets.java
package org.glassfish.jersey.examples.linking;
import java.net.URI;
import java.util.List;
import javax.ws.rs.core.Link;
import javax.xml.bind.annotation.XmlRootElement;
import org.glassfish.jersey.linking.InjectLink;
import org.glassfish.jersey.linking.InjectLinks;
#XmlRootElement()
public class Widgets {
#InjectLink(resource=WidgetsResource.class)
URI u;
#InjectLinks({#InjectLink(resource=WidgetsResource.class, rel = "self")})
List<Link> links;
public Widgets() {}
}
I put a breakpoint in the resource code and examined the object being returned. it.links and it.u are both null. There's nothing injected.
WidgetsResource.java
#Path("widgets")
public class WidgetsResource {
#GET
public Widgets get() {
Widgets it = new Widgets();
return it;
}
}
Maven dependencies:
<dependencies>
<dependency>
<groupId>org.glassfish.jersey.containers</groupId>
<artifactId>jersey-container-servlet</artifactId>
<version>${jersey.version}</version>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.ext</groupId>
<artifactId>jersey-declarative-linking</artifactId>
<version>${jersey.version}</version>
</dependency>
<dependency>
<groupId>org.glassfish</groupId>
<artifactId>javax.el</artifactId>
<version>2.2.4</version>
</dependency>
<dependency>
<groupId>javax.el</groupId>
<artifactId>javax.el-api</artifactId>
<version>2.2.4</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.datatype</groupId>
<artifactId>jackson-datatype-joda</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.jaxrs</groupId>
<artifactId>jackson-jaxrs-json-provider</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.jaxrs</groupId>
<artifactId>jackson-jaxrs-xml-provider</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.jaxrs</groupId>
<artifactId>jackson-jaxrs-yaml-provider</artifactId>
<version>${jackson.version}</version>
</dependency>
</dependencies>
<properties>
<jersey.version>2.21</jersey.version>
<jackson.version>2.6.1</jackson.version>
</properties>
web.xml:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
id="WebApp_ID" version="3.1">
<display-name>Server</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>Jersey REST Service</servlet-name>
<servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
<init-param>
<param-name>javax.ws.rs.Application</param-name>
<param-value>org.glassfish.jersey.examples.linking.Server</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>Jersey REST Service</servlet-name>
<url-pattern>/rest/v1/*</url-pattern>
</servlet-mapping>
</web-app>
The application object:
package org.glassfish.jersey.examples.linking;
import org.glassfish.jersey.linking.DeclarativeLinkingFeature;
import org.glassfish.jersey.server.ResourceConfig;
public class Server extends ResourceConfig {
public Server() {
packages("org.glassfish.jersey.examples.linking",
"com.fasterxml.jackson.jaxrs")
.register(DeclarativeLinkingFeature.class);
}
}
It appears that the #InjectLink(s) annotations are simply being ignored. There must be some magic setting I'm missing, but I've done everything the Jersey doc says to do.
I tried with both Servlet 2.x (shown) and Servlet 3.x (using #ApplicationPath) and that made no difference.
Some of you will notice from my package names that I also tried the slightly more advanced, but no more successful, Jersey declarative linking example (https://github.com/jersey/jersey/tree/master/examples/declarative-linking). Some of the basic fields were returned, but all of the injected links were missing or null.
.../Server/rest/v1/items/1 produced:
{
"id": "1",
"nextId": "2",
"prevId": "0",
"prev": true,
"next": true
}
FYI - I'm running Java 1.8.0_60, Eclipse Mars, and Tomcat 8.0.26. There are no errors, no warnings and no runtime messages. I'm completely stumped. Anyone have any pointers???

Answer 1

I have added the following to my servlet config:
`<init-param>
<param-name>jersey.config.server.provider.classnames</param-name>
<param-value>
org.glassfish.jersey.linking.DeclarativeLinkingFeature
</param-value>
</init-param>'
and the links were rendered in the json response.

Answer 2

For information, if you do not want to use web.xml config file, you can do that:
import javax.ws.rs.ApplicationPath;
import org.glassfish.jersey.linking.DeclarativeLinkingFeature;
import org.glassfish.jersey.server.ResourceConfig;
#ApplicationPath("rest/v1")
public class MyApp extends ResourceConfig {
public MyApp () {
packages("the.package.where.your.services.are.located")
.register(DeclarativeLinkingFeature.class);
}
}