src/java.base/share/classes/java/lang/System.java

rev 52881 : 8214971: Replace use of string.equals("") with isEmpty()
Reviewed-by: jlaskey, prappo, lancea, dfuchs, redestad

@@ -968,11 +968,11 @@
 
     private static void checkKey(String key) {
         if (key == null) {
             throw new NullPointerException("key can't be null");
         }
-        if (key.equals("")) {
+        if (key.isEmpty()) {
             throw new IllegalArgumentException("key can't be empty");
         }
     }
 
     /**