Handling Post requests in Jersey/GWT application - maven

Question

I'm trying to add some REST endpoints to Webprotege project, GWT based, using a Jersey based servlet (which I'm learning now).
Adding some Maven dependencies and the servlet declaration in the web.xml file, I got it working.
My iussue is now hanling POST request, since the incoming http body is not unmarshalled in the class which maps it.
GET requests work.
Here's my dummy class which will containt all RESTFul controller:
#Path("hellos")
public class XlodAPIServiceImpl {
#XmlRootElement
public class Request{
#XmlElement
private String message;
public Request(String message) {
super();
this.message = message;
}
public Request(){}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
#POST
#Produces("application/json")
#Consumes("application/json")
public Collection<String> get(Request request) {
try {
return new ArrayList<String>();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
return new ArrayList<String>();
}
}
Server got me always 500, without any stacktrace/useful tip.
The iussue may be related to JSON unmarshalling, since also GET requests with JSON responses set work as expected.
This is what I added in the pom.xml file:
<dependency>
<groupId>javax.ws.rs</groupId>
<artifactId>javax.ws.rs-api</artifactId>
<version>2.0</version>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.containers</groupId>
<!-- if your container implements Servlet API older than 3.0, use "jersey-container-servlet-core" -->
<artifactId>jersey-container-servlet-core</artifactId>
<version>2.7</version>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.media</groupId>
<artifactId>jersey-media-json-jackson</artifactId>
<version>2.7</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.jaxrs</groupId>
<artifactId>jackson-jaxrs-json-provider</artifactId>
<version>2.3.2</version>
</dependency>
while here's the web.xml:
<servlet>
<servlet-name>MyApplication</servlet-name>
<servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
<init-param>
<param-name>jersey.config.server.provider.packages</param-name>
<param-value>
edu.stanford.bmir.protege.web.server
</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>MyApplication</servlet-name>
<url-pattern>/api/*</url-pattern>
</servlet-mapping>
Suggestions?
Thanks in advance,
FB