Junit test cases for REST API

I need to write a junit test case for REST API.Am new to Junit test case can anyone help me to understand and write the test cases for REST APIs. Note: REST Application is NOT a spring based application.

@Path("/watchlistService") public class sample {

private static final MCPLogger LOGGER =
        MCPLoggerFactory.getLogger(WatchlistServiceAPI.class);
@Inject
private Config configModel;
@Inject
private UIConfig configUIModel;

@EJB
private CaseDatabaseBean caseDatabase;

@EJB
IDBAccess dbAccess;

@EJB
WatchlistServiceBean watchlistService;

@EJB
private IWatchlistSecurity watchlistSecurity;

@EJB
private TrackBean trackBean;
@EJB
IWatchlistAccess watchlistAccess;

@EJB
private DBModelValidationBean modelValidation;

@EJB
private IMVIAuditLogger mviAuditLogger;
ThreadLocal<Integer> threadLocalValue = new ThreadLocal<>();
private String getRequestUserName( @Context HttpServletRequest req )
{
    return req.getUserPrincipal() == null ? "null" :
            req.getUserPrincipal().getName();
}
@GET
@Path("/personattributes")
@Produces("application/json;charset=utf-8")
public Response getWatchlistPersonAttributes(@Context HttpServletRequest req) {
    try {
        JSONObject jsonPAttr = new JSONObject();
        JSONArray jsonAttributes = new JSONArray();
        for(WatchlistPersonAttribute attribute :
                watchlistAccess.getPersonAttributes()) {
            JSONObject jsonAttribute = new JSONObject();
            jsonAttribute.put("name", attribute.name);
            jsonAttribute.put("type", attribute.type.toString());
            jsonAttribute.put("required", attribute.required);
            jsonAttributes.put(jsonAttribute);
        }
        jsonPAttr.put("attributes", jsonAttributes);
        WatchlistPersonDescriptor descriptor =
                watchlistAccess.getPersonDescriptor();
        jsonPAttr.put("descriptor", descriptor.descriptor);
        JSONArray jsonDescriptorArguments = new JSONArray();
        for(int i = 0; i < descriptor.arguments.length; ++i) {
            jsonDescriptorArguments.put(descriptor.arguments[i]);
        }
        jsonPAttr.put("descriptorArguments", jsonDescriptorArguments);
        return Response.status(200).entity(jsonPAttr.toString()).build();
    } catch (Exception e) {
        return getReturnError("Couldn't retreive watchlist person attributes: " + e.getMessage());
    }
}

}

I need to write a junit test case for REST API.Am new to Junit test case can anyone help me to understand and write the test cases for REST APIs. Note: REST Application is NOT a spring based application.