Restart callCount after each fetch

spring-app/src/main/java/com/example/demo/DataController.java

@@ -15,9 +15,12 @@ class DataController {
         return ret;
     }
 
-    @GetMapping("/metrics")
+    @GetMapping(value = "/metrics", produces = "text/plain")
     String metrics() {
-        return "# HELP calls_count Total number of calls\n# TYPE calls_count counter\ncalls_count " + callsCount;
+        String returnMessage = "# HELP calls_count Total number of calls\n# TYPE calls_count counter\ncalls_count "
+                + callsCount + "\n";
+        callsCount = 0;
+        return returnMessage;
     }
 }