Fix Sonar warnings

smp-server-library/src/main/java/eu/europa/ec/edelivery/smp/servlet/WebConstants.java

 package eu.europa.ec.edelivery.smp.servlet;
 
+/**
+ * The REST API endpoint constants
+ *
+ * @author Joze Rihtarsic
+ * @since 4.1
+ */
 public class WebConstants {
-
-    public static int HTTP_RESPONSE_CODE_CREATED= 201;
-    public static int HTTP_RESPONSE_CODE_UPDATED= 200;
-
+    public static final int HTTP_RESPONSE_CODE_CREATED= 201;
+    public static final int HTTP_RESPONSE_CODE_UPDATED= 200;
     public static final String HTTP_PARAM_DOMAIN="Domain";
     public static final String HTTP_PARAM_RESOURCE_TYPE="Resource-Type";
     public static final String HTTP_PARAM_OWNER="ServiceGroup-Owner";
+
+    private WebConstants() {
+    }
+
 }