Bring draft status to PatchSetAttribute

Thereby, stream event consumers can differentiate between events that
are tied to a draft patch set and those that are not.

Change-Id: Idbdcfc979f2383de0708560bf2e148fcc51d612f

Documentation/json.txt

@@ -115,6 +115,8 @@ author:: Author of this patchset in <<account,account attribute>>.
 createdOn:: Time in seconds since the UNIX epoch when this patchset
 was created.
 
+isDraft:: Whether or not the patch set is a draft patch set.
+
 approvals:: The <<approval,approval attribute>> granted.
 
 comments:: All comments for this patchset in <<patchsetcomment,patchsetComment attributes>>.

gerrit-server/src/main/java/com/google/gerrit/server/data/PatchSetAttribute.java

@@ -24,6 +24,7 @@ public class PatchSetAttribute {
   public AccountAttribute uploader;
   public Long createdOn;
   public AccountAttribute author;
+  public boolean isDraft;
 
   public List<ApprovalAttribute> approvals;
   public List<PatchSetCommentAttribute> comments;

gerrit-server/src/main/java/com/google/gerrit/server/events/EventFactory.java

@@ -361,6 +361,7 @@ public class EventFactory {
     p.ref = patchSet.getRefName();
     p.uploader = asAccountAttribute(patchSet.getUploader());
     p.createdOn = patchSet.getCreatedOn().getTime() / 1000L;
+    p.isDraft = patchSet.isDraft();
     final PatchSet.Id pId = patchSet.getId();
     try {
       final ReviewDb db = schema.open();