EditInfo: Include the change edit ref

When a change edit is retrieved using the API, there is no way to get
the edit's ref. The ref is included as part of the `fetch` info, but
this is not filled for calls via the API.

Add a `ref` field in the info.

Bug: Issue 10263
Change-Id: I1e637a0d372d30e2102fbf196166d4bddff111d2

Documentation/rest-api-changes.txt

@@ -2498,7 +2498,8 @@ provided fetch info map is also included.
        "message":"Use an EventBus to manage star icons\n\nImage widgets that need to ..."
     },
     "base_patch_set_number":1,
-    "base_revision":"c35558e0925e6985c91f3a16921537d5e572b7a3"
+    "base_revision":"c35558e0925e6985c91f3a16921537d5e572b7a3",
+    "ref":"refs/users/01/1000001/edit-76482/1"
   }
 ----
 
@@ -4734,6 +4735,7 @@ resulting change edit is returned.
       },
       "base_patch_set_number":1,
       "base_revision":"674ac754f91e64a0efb8087e59a176484bd534d1"
+      "ref":"refs/users/01/1000001/edit-42622/1"
     }
 ----
 
@@ -6182,6 +6184,7 @@ The `EditInfo` entity contains information about a change edit.
 link:#commit-info[CommitInfo] entity.
 |`base_patch_set_number`||The patch set number of the patch set the change edit is based on.
 |`base_revision`        ||The revision of the patch set the change edit is based on.
+|`ref`                  ||The ref of the change edit.
 |`fetch`                |optional|
 Information about how to fetch this patch set. The fetch information is
 provided as a map that maps the protocol name ("`git`", "`http`",

gerrit-extension-api/src/main/java/com/google/gerrit/extensions/common/EditInfo.java

@@ -20,6 +20,7 @@ public class EditInfo {
   public CommitInfo commit;
   public int basePatchSetNumber;
   public String baseRevision;
+  public String ref;
   public Map<String, FetchInfo> fetch;
   public Map<String, FileInfo> files;
 }

gerrit-server/src/main/java/com/google/gerrit/server/edit/ChangeEditJson.java

@@ -52,6 +52,7 @@ public class ChangeEditJson {
     out.commit = fillCommit(edit.getEditCommit());
     out.baseRevision = edit.getBasePatchSet().getRevision().get();
     out.basePatchSetNumber = edit.getBasePatchSet().getPatchSetId();
+    out.ref = edit.getRefName();
     if (downloadCommands) {
       out.fetch = fillFetchMap(edit);
     }