Gson deserialization fails JAX-RS using Jersey

Question

I am trying to implement JAX-RS service using Jersey and GSON as the JSON provider. The provider is similar to what is outlined in https://gist.github.com/hstaudacher/4967804. My entity class looks as follows:

public class Company implements Serializable{

    public static final String DEFAULT_COMPANY = "DEFAULT_COMPANY";

    @Expose
    @SerializedName("company_id")
    private String mcompanyId;

    private ConcurrentHashMap<String, User> m_userMap = new ConcurrentHashMap<String, User>();

    private ConcurrentHashMap<String, ServiceProvider> m_spMap = new ConcurrentHashMap<String, ServiceProvider>();

    private static ConcurrentHashMap<String, Company> s_companyMap = new ConcurrentHashMap<String, Company>();

    public Company() {
        super();
        // TODO Auto-generated constructor stub
    }

    ... additional code omitted for brevity

The corresponding JAX-RS service handler is

@Path("/company")
public class CompanyService {

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public ArrayList<Company> getCompany() {
        return Company.getAll();
    }


    @POST
    @Consumes(MediaType.APPLICATION_JSON)
    @Produces(MediaType.APPLICATION_JSON)
    public ArrayList<Company> addCompany(Company c){
        System.out.print("Company id ==> " + c.getCompanyId());
        Company.getInstance(c.getCompanyId());
        return Company.getAll();
    }
}

When I invoke this with the following JSON payload

{
   "company_id":"test123"
}

It fails. When I look at the logs I see that c.getCompanyId() returns as NULL.

Any ideas as to what I am missing here ?