Add CHANGES.txt for HADOOP-11481

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -478,6 +478,9 @@ Release 2.7.0 - UNRELEASED
     HADOOP-11465. Fix findbugs warnings in hadoop-gridmix. (Varun Saxena via
     Arpit Agarwal)
 
+    HADOOP-11481. ClassCastException while using a key created by keytool to
+    create encryption zone. (Charles Lamb via Colin P. Mccabe)
+
   OPTIMIZATIONS
 
     HADOOP-11323. WritableComparator#compare keeps reference to byte array.