Follow up 137982

Updates comment explaining why we sort types by name in run-test
031-class-attributes.

Bug: 19499481
Change-Id: I1ee425a24dffd55d134effc6857e2c0ca368422a
diff --git a/test/031-class-attributes/src/ClassAttrs.java b/test/031-class-attributes/src/ClassAttrs.java
index 977a05f..c2e41c5 100644
--- a/test/031-class-attributes/src/ClassAttrs.java
+++ b/test/031-class-attributes/src/ClassAttrs.java
@@ -330,8 +330,9 @@
         for (Type t : types) {
           typeStringList.add(t.toString());
         }
-        // Sort types alphabetically so they're always printed in the same order, whichever
-        // tool generated the DEX file of the test.
+        // Sort types alphabetically so they're always printed in the same order.
+        // For instance, Class.getClasses() does not guarantee any order for the
+        // returned Class[].
         Collections.sort(typeStringList);
 
         StringBuilder stb = new StringBuilder();