Fix missing reason param in ChangeRestoredEvent

'reason' param in ChangeRestoredEvent got accidentally dropped
 by Id429d8cd9e626d88c1f81954e6b37488896f9b90.

This CL adds the 'reason' param back.

Change-Id: I0dbd47ef3ab737b1be8bd2c4707dbf1a8f5b57cf
diff --git a/src/main/java/com/googlesource/gerrit/plugins/its/base/util/PropertyExtractor.java b/src/main/java/com/googlesource/gerrit/plugins/its/base/util/PropertyExtractor.java
index e165baf..5d50662 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/its/base/util/PropertyExtractor.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/its/base/util/PropertyExtractor.java
@@ -103,6 +103,7 @@
   private Map<String, Set<String>> extractFrom(
       ChangeRestoredEvent event, Map<String, String> common) {
     common.putAll(propertyAttributeExtractor.extractFrom(event.restorer.get(), "restorer"));
+    common.put("reason", event.reason);
     return extractMapFrom(event, common);
   }