Use Xstream2#addCriticalField directly instead of via reflection

Since Jenkins 2.85 (https://jenkins.io/changelog/#v2.85) this method is available for plugins.

pom.xml

@@ -36,7 +36,7 @@
   </licenses>
 
   <properties>
-    <jenkins.version>2.60.3</jenkins.version>
+    <jenkins.version>2.85</jenkins.version>
     <java.level>8</java.level>
     <workflow.version>1.0</workflow.version> <!-- only for testing purpose -->
   </properties>

src/main/java/org/jenkinsci/plugins/authorizeproject/AuthorizeProjectProperty.java

@@ -39,8 +39,6 @@
 import hudson.model.Queue;
 import hudson.util.FormApply;
 import java.io.IOException;
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
@@ -49,8 +47,6 @@
 import javax.annotation.CheckForNull;
 import javax.annotation.Nonnull;
 import javax.servlet.ServletException;
-
-import hudson.util.XStream2;
 import jenkins.model.Jenkins;
 import jenkins.model.TransientActionFactory;
 import net.sf.json.JSONObject;
@@ -138,10 +134,8 @@ public Authentication authenticate(Queue.Item item) {
      * This method is responsible for ensuring that POSTing config.xml respects the defined strategy.
      */
     @Initializer(after = InitMilestone.PLUGINS_STARTED)
-    public static void setStrategyCritical() throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
-        //TODO the reflection could be removed when the addCriticalField will be un-restricted (PR: https://github.com/jenkinsci/jenkins/pull/3066)
-        Method method = XStream2.class.getMethod("addCriticalField", Class.class, String.class);
-        method.invoke(Items.XSTREAM2, AuthorizeProjectProperty.class, "strategy");
+    public static void setStrategyCritical() {
+        Items.XSTREAM2.addCriticalField(AuthorizeProjectProperty.class, "strategy");
     }
 
     /**