fix response format

spring-security-rest-full/src/main/java/org/baeldung/web/controller/RootController.java

@@ -1,6 +1,7 @@
 package org.baeldung.web.controller;
 
 import java.net.URI;
+import java.util.Map;
 
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
@@ -42,13 +43,13 @@ public class RootController {
 
     @RequestMapping(value = "/metric", method = RequestMethod.GET)
     @ResponseBody
-    public String getMetric() {
+    public Map getMetric() {
         return metricService.getFullMetric();
     }
 
     @RequestMapping(value = "/status-metric", method = RequestMethod.GET)
     @ResponseBody
-    public String getStatusMetric() {
+    public Map getStatusMetric() {
         return metricService.getStatusMetric();
     }
 

spring-security-rest-full/src/main/java/org/baeldung/web/metric/IMetricService.java

@@ -1,12 +1,14 @@
 package org.baeldung.web.metric;
 
+import java.util.Map;
+
 public interface IMetricService {
 
     void increaseCount(final String request, final int status);
 
-    String getFullMetric();
+    Map getFullMetric();
 
-    String getStatusMetric();
+    Map getStatusMetric();
 
     Object[][] getGraphData();
 }

spring-security-rest-full/src/main/java/org/baeldung/web/metric/MetricService.java

@@ -34,13 +34,13 @@ public class MetricService implements IMetricService {
     }
 
     @Override
-    public String getFullMetric() {
-        return metricMap.entrySet().toString();
+    public Map getFullMetric() {
+        return metricMap;
     }
 
     @Override
-    public String getStatusMetric() {
-        return statusMetric.entrySet().toString();
+    public Map getStatusMetric() {
+        return statusMetric;
     }
 
     @Override