[FIXED JENKINS-24452] Don't export arbitrary unexportable exceptions

core/src/main/java/hudson/slaves/OfflineCause.java

@@ -103,7 +103,6 @@ public abstract class OfflineCause {
      * Caused by unexpected channel termination.
      */
     public static class ChannelTermination extends OfflineCause {
-        @Exported
         public final Exception cause;
 
         public ChannelTermination(Exception cause) {