java - Spring Boot RestTemplate.postForObject to Firebase Messaging not returning -

i'm trying tie google's firebase messaging platform app, , i'm trying use spring's built in resttemplate rest abstraction simplify it.

i'm trying to:

resttemplate resttemplate = new resttemplate(); resttemplate.getmessageconverters().add(new gsonhttpmessageconverter());  multivaluemap<string, string> headers = new linkedmultivaluemap<>(); headers.add("authorization", "key=" + constants.firebase_server_key); headers.add("content-type", "application/json");  httpentity<firebasepost> entity = new httpentity<>(fbp, headers); uri uri; uri = new uri(firebaseapi);  firebaseresponse fbr = resttemplate.postforobject(uri, entity, firebaseresponse.class); 

the firebasepost object contains required fields post message api: firebase api - , have verified request entity works posting string.class, response unmarshalled json.

however, trying response marshall directly firebaseresponse object, call postforobject hangs , never returns.

@jsonignoreproperties(ignoreunknown = true) public class firebaseresponse {      public integer multicast_id;     public integer success;     public integer failure;     public integer canonical_ids;      public firebaseresponse() {} } 

i'm having trouble understanding why call never completes. love able have response directly object.

try this:

    package yourpackage;      import com.fasterxml.jackson.annotation.jsonignoreproperties;      @jsonignoreproperties(ignoreunknown = true)     public class firebaseresponse {          private long multicast_id;         private integer success;         private integer failure;         private object canonical_ids;          public firebaseresponse() {         }          //---- use 1 ----         public boolean is_success() {             if (getsuccess() == 1) {                 return true;             } else {                 return false;             }         }          public long getmulticast_id() {             return multicast_id;         }          public void setmulticast_id(long multicast_id) {             this.multicast_id = multicast_id;         }          public integer getsuccess() {             return success;         }          public void setsuccess(integer success) {             this.success = success;         }          public integer getfailure() {             return failure;         }          public void setfailure(integer failure) {             this.failure = failure;         }          public object getcanonical_ids() {             return canonical_ids;         }          public void setcanonical_ids(object canonical_ids) {             this.canonical_ids = canonical_ids;         }          @override         public string tostring() {             return "firebaseresponse{" +                     "multicast_id=" + multicast_id +                     ", success=" + success +                     ", failure=" + failure +                     ", canonical_ids=" + canonical_ids +                     '}';         }     }  //--------------- usage ------------------                 arraylist<clienthttprequestinterceptor> interceptors = new arraylist<>();             interceptors.add(new headerrequestinterceptor("authorization", "key=" + firebase_server_key));             interceptors.add(new headerrequestinterceptor("content-type", "application/json"));             resttemplate.setinterceptors(interceptors);           jsonobject body = new jsonobject();             // jsonarray registration_ids = new jsonarray();             // body.put("registration_ids", registration_ids);             body.put("to", "cfw930czxxxxxxxxxxxxxxxxxxxxxxxxxxipdo-bjhlachrqqzc0asxlrfkdmhv_anbxkrzlnxxxxxxxxxxx59spw4rw-5mtwkkzxxxxxxxgxll-llijuujpwzplglpji_");             body.put("priority", "high");             // body.put("dry_run", true);              jsonobject notification = new jsonobject();             notification.put("body", "body string here");             notification.put("title", "title string here");             // notification.put("icon", "myicon");              jsonobject data = new jsonobject();             data.put("key1", "value1");             data.put("key2", "value2");              body.put("notification", notification);             body.put("data", data);                httpentity<string> request = new httpentity<>(body.tostring());              firebaseresponse firebaseresponse = resttemplate.postforobject("https://fcm.googleapis.com/fcm/send", request, firebaseresponse.class);             log.info("response is: " + firebaseresponse.tostring());               return new responseentity<>(firebaseresponse.tostring(), httpstatus.ok);  //--------------- helper class ------------------          import org.springframework.http.httprequest;     import org.springframework.http.client.clienthttprequestexecution;     import org.springframework.http.client.clienthttprequestinterceptor;     import org.springframework.http.client.clienthttpresponse;     import org.springframework.http.client.support.httprequestwrapper;      import java.io.ioexception;      public class headerrequestinterceptor implements clienthttprequestinterceptor {          private final string headername;          private final string headervalue;          public headerrequestinterceptor(string headername, string headervalue) {             this.headername = headername;             this.headervalue = headervalue;         }          @override         public clienthttpresponse intercept(httprequest request, byte[] body, clienthttprequestexecution execution) throws ioexception {             httprequest wrapper = new httprequestwrapper(request);             wrapper.getheaders().set(headername, headervalue);             return execution.execute(wrapper, body);         }     }