Merge pull request #1960 from varmenise/IdleOfflineCause-ClassImplementation

create a specific implementation for Idle Offline Cause

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

@@ -155,4 +155,14 @@ public abstract class OfflineCause {
             this.message = message;
         }
     }
+
+    /**
+     * Caused by idle period.
+     * @since TODO
+     */
+    public static class IdleOfflineCause extends SimpleOfflineCause {
+        public IdleOfflineCause () {
+            super(hudson.slaves.Messages._RetentionStrategy_Demand_OfflineIdle());
+        }
+    }
 }

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

@@ -267,7 +267,7 @@ public abstract class RetentionStrategy<T extends Computer> extends AbstractDesc
                     // we've been idle for long enough
                     logger.log(Level.INFO, "Disconnecting computer {0} as it has been idle for {1}",
                             new Object[]{c.getName(), Util.getTimeSpanString(idleMilliseconds)});
-                    c.disconnect(OfflineCause.create(Messages._RetentionStrategy_Demand_OfflineIdle()));
+                    c.disconnect(new OfflineCause.IdleOfflineCause());
                 } else {
                     // no point revisiting until we can be confident we will be idle
                     return TimeUnit.MILLISECONDS.toMinutes(TimeUnit.MINUTES.toMillis(idleDelay) - idleMilliseconds);