java - Customer header is not coming in the response -

in jax-rs(jersey + jetty) application, i've added custom headers response can use @ client side. i'm using responsebuilder achieve this.

     @provider public class customexceptionmapper implements exceptionmapper<customexception> {      private static final logger logger = loggerfactory.getlogger(customexceptionmapper.class);      @context     private httpheaders headers;       @override     public response toresponse(customexception exception) {          string errorkey = null;         string errorargs[] = null;          // log stack trace         logger.error("an error occurred during operation.", exception);         if (exception instanceof metadataserverexception) {                 errorkey = exceptionmapperutil.checkfordbexception(exception.getcause());             if (errorkey != null) {                 return response.status(response.status.internal_server_error)                         .entity(messagesourceutils.getmessage(errorkey, errorargs, exceptionmapperutil.getlocale(headers))).type(mediatype.text_plain).build();             }         }          if(errorcodes.internal_server_error.equals(exception.getmessagekey()) &&                  (exception.getmessagearguments() == null || exception.getmessagearguments().length==0) ){             exception.setmessagearguments(new object[]{"while executing operation"});           }         // prepare response sent client         return response.status(responsecodemapper.maptostatuscode(exception)).                 entity(exception.getmessage(exceptionmapperutil.getlocale(headers))).                 type(mediatype.text_plain).header("errorcode", exception.getmessagekey()).                 build();     } } 

and also, i've confirmed that response object getting built properly. however, reason, returned response doesn't contain custom header. clues to going wrong ?