Jpos Rest tutorial is giving the error 503 Service Unavailable

Question

I just started exploring JPos. I am trying to implement Rest tutorial. /echo call is giving me 503 Service unavailable. I am doing exactly what the tutorial is suggesting.

App.java

package org.jpos.rest;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import org.glassfish.jersey.jackson.JacksonFeature;
import org.glassfish.jersey.server.ResourceConfig;
import javax.ws.rs.ext.ContextResolver;
public class App extends ResourceConfig {
    public App() {
        super();

        register(JacksonFeature.class);
        register(new Resolver());
        packages("org.jpos.rest");
    }
     class Resolver implements ContextResolver<ObjectMapper> {
        final ObjectMapper defaultObjectMapper = createDefaultMapper();
        @Override
        public ObjectMapper getContext(Class<?> type) {
            return defaultObjectMapper;
        }
        private ObjectMapper createDefaultMapper() {
            final ObjectMapper mapper = new ObjectMapper();
            mapper.configure(JsonGenerator.Feature.WRITE_BIGDECIMAL_AS_PLAIN, true);
            mapper.configure(JsonGenerator.Feature.ESCAPE_NON_ASCII, true);
            mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
            mapper.enable(SerializationFeature.INDENT_OUTPUT);
          
            return mapper;
        }
    }
}

Echo.java

package org.jpos.rest;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import java.util.HashMap;
import java.util.Map;
@Path("/echo")
public class Echo {
    @GET
    @Produces({MediaType.APPLICATION_JSON})
    public Response echoGet(){
        Map<String, Object> resp = new HashMap<>();
        resp.put("success", "true");
        return Response.ok(resp, MediaType.APPLICATION_JSON)
                .status(Response.Status.OK)
                .build();
    }
}

Project structure

My output

I have debugged the code and it is reaching App.java but it isn't reaching Echo.java