Merge branch 'stable-2.15'

* stable-2.15:
  HookQueue: Rename constructor 'queue' argument to avoid confusion
  Add submit hook
  Module: Bind listeners in alphabetical order
  Annotate RefUpdate and CommitReceived as Singleton
  Reword documentation of ref-update and commit-received hooks
  Improve hooks documentation structure

Change-Id: I163ca67fb412b098e0556f4374d54bde65affc00

src/main/java/com/googlesource/gerrit/plugins/hooks/CommitReceived.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/hooks/CommitReceived.java b/src/main/java/com/googlesource/gerrit/plugins/hooks/CommitReceived.java
index b03a77b..74a0817 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/hooks/CommitReceived.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/hooks/CommitReceived.java
@@ -51,7 +51,7 @@
     args.add("--project", projectName);
     args.add("--refname", refname);
     args.add("--uploader", receiveEvent.user.getNameEmail());
-    args.add("--uploader-username", receiveEvent.user.getUserName());
+    args.add("--uploader-username", receiveEvent.user.getUserName().orElse(null));
     args.add("--oldrev", old.name());
     args.add("--newrev", receiveEvent.commit.name());
     args.add("--cmdref", commandRef);

src/main/java/com/googlesource/gerrit/plugins/hooks/RefUpdate.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/hooks/RefUpdate.java b/src/main/java/com/googlesource/gerrit/plugins/hooks/RefUpdate.java
index 7eedfa5..90a1b93 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/hooks/RefUpdate.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/hooks/RefUpdate.java
@@ -49,7 +49,7 @@
     HookArgs args = hookFactory.createArgs();
     args.add("--project", projectName);
     args.add("--uploader", refEvent.user.getNameEmail());
-    args.add("--uploader-username", refEvent.user.getUserName());
+    args.add("--uploader-username", refEvent.user.getUserName().orElse(null));
     args.add("--oldrev", getObjectId(refEvent.command.getOldId()).getName());
     args.add("--newrev", getObjectId(refEvent.command.getNewId()).getName());
     args.add("--refname", refEvent.command.getRefName());

src/main/java/com/googlesource/gerrit/plugins/hooks/Submit.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/hooks/Submit.java b/src/main/java/com/googlesource/gerrit/plugins/hooks/Submit.java
index 8e2f1e0..7474553 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/hooks/Submit.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/hooks/Submit.java
@@ -51,7 +51,7 @@
     args.add("--project", projectName);
     args.add("--branch", destBranch.get());
     args.add("--submitter", caller.getNameEmail());
-    args.add("--submitter-username", caller.getUserName());
+    args.add("--submitter-username", caller.getUserName().get());
     args.add("--patchset", patchSetId.get());
     args.add("--commit", commit.getId().name());