review feedback

Author: Justin Brinegar

hadoop-common-project/hadoop-auth/src/main/java/org/apache/hadoop/util/subject/GetSubjectNg.java renamed to hadoop-common-project/hadoop-auth/src/main/java/org/apache/hadoop/util/subject/GetSubjectJava18AndAbove.java

@@ -25,10 +25,10 @@
 /**
  * Indirectly calls Subject.current(), which exists in Java 18 and above only
  */
-class GetSubjectNg implements HiddenGetSubject {
+class GetSubjectJava18AndAbove implements HiddenGetSubject {
     private final Method currentMethod;
 
-    GetSubjectNg() {
+    GetSubjectJava18AndAbove() {
         try {
             currentMethod = Subject.class.getMethod("current");
         } catch (NoSuchMethodException e) {

hadoop-common-project/hadoop-auth/src/main/java/org/apache/hadoop/util/subject/SubjectAdapter.java

@@ -18,6 +18,9 @@
 
 package org.apache.hadoop.util.subject;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import javax.security.auth.Subject;
 
 /**
@@ -26,14 +29,15 @@
  * This class helps use the newer API if available, without raising the language level.
  */
 public class SubjectAdapter {
+    private static Logger log = LoggerFactory.getLogger(SubjectAdapter.class);
     private static final HiddenGetSubject instance;
     static {
         int version = 0;
         try {
             version = Integer.parseInt(System.getProperty("java.specification.version"));
         } catch (Throwable ignored) {}
         if (version >= 18) {
-            instance = new GetSubjectNg();
+            instance = new GetSubjectJava18AndAbove();
         } else {
             instance = new ClassicGetSubject();
         }
@@ -45,8 +49,12 @@ public static Subject getSubject() {
         return instance.getSubject();
     }
 
-    // the main is included so that this is trivially tested using multiple JDKs outside the scope of test sources
+    /**
+     * This main method is included so that this is trivially tested using multiple JDKs outside the scope test sources
+     * @param args ignored
+     */
     public static void main(String[] args) {
-        System.out.println("Current subject is " + getSubject());
+        final Subject theSubject = getSubject();
+        log.info("Current subject is {}", theSubject);
     }
 }