Fix inclusion of username if detailed account information is requested

The documentation of AccountInfo claims that the username is included
if detailed account information is requested but this was not the
case.

Change-Id: Ic28cadb6b7236ce69b60cb9d237fe18eae01e8e0
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
diff --git a/Documentation/rest-api-changes.txt b/Documentation/rest-api-changes.txt
index 08411f5..9b83a6f 100644
--- a/Documentation/rest-api-changes.txt
+++ b/Documentation/rest-api-changes.txt
@@ -209,8 +209,8 @@
 
 [[detailed-accounts]]
 --
-* `DETAILED_ACCOUNTS`: include `_account_id` and `email` fields when
-  referencing accounts.
+* `DETAILED_ACCOUNTS`: include `_account_id`, `email` and `username`
+  fields when referencing accounts.
 --
 
 [[messages]]
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/account/AccountInfo.java b/gerrit-server/src/main/java/com/google/gerrit/server/account/AccountInfo.java
index cde59e1..7498002 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/account/AccountInfo.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/account/AccountInfo.java
@@ -38,6 +38,7 @@
         Collections.unmodifiableSet(EnumSet.of(
             FillOptions.NAME,
             FillOptions.EMAIL,
+            FillOptions.USERNAME,
             FillOptions.AVATARS));
 
     public interface Factory {