fix support for master branch

Change-Id: Iada84ddd8e6effc3208fdb9d121ddfc39748d46d

src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java b/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java
index bf7143c..b3c9062 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java
@@ -81,7 +81,7 @@
     }
     StringBuilder avatarUrl = new StringBuilder();
     String userReplacedAvatarURL = replaceInUrl(USER_PLACEHOLDER,
-        externalAvatarUrl, forUser.getUserName());
+        externalAvatarUrl, forUser.getUserName().get());
     avatarUrl.append(replaceInUrl(EMAIL_PLACEHOLDER, userReplacedAvatarURL,
         forUser.getAccount().getPreferredEmail()));
     if (imageSize > 0 && sizeParameter != null) {
@@ -99,7 +99,7 @@
   @Override
   public String getChangeAvatarUrl(IdentifiedUser forUser) {
     String userReplacedAvatarChangeURL = replaceInUrl(USER_PLACEHOLDER,
-        avatarChangeUrl, forUser.getUserName());
+        avatarChangeUrl, forUser.getUserName().get());
     return replaceInUrl(EMAIL_PLACEHOLDER, userReplacedAvatarChangeURL,
         forUser.getAccount().getPreferredEmail());
   }