Fix NPE

Although it seems strange to have a RefModel with a referenced object
but a null Ref, Gitblit uses such RefModels for instance in
JGitUtils.getNotesOnCommit().

Be careful to do something sensible when that Ref is null.

Author: tomaswolf

docu/index.md

@@ -5,7 +5,7 @@ with full SSO through Gerrit.
 
 * License: [Apache Public License 2.0](http://www.apache.org/licenses/LICENSE-2.0)
 * [Home page](https://github.com/tomaswolf/gerrit-gitblit-plugin)
-* Installed plugin version: <em id='gerrit-gitblit-current-version'>2.12.171.5-SNAPSHOT</em> &mdash; <a id='gerrit-gitblit-version-check' style='display:none;' href='#'>Check for updates</a>
+* Installed plugin version: <em id='gerrit-gitblit-current-version'>2.12.171.6-SNAPSHOT</em> &mdash; <a id='gerrit-gitblit-version-check' style='display:none;' href='#'>Check for updates</a>
 
 For a list of contributors, see at [GitHub](https://github.com/tomaswolf/gerrit-gitblit-plugin/graphs/contributors).
 
@@ -111,6 +111,6 @@ Report bugs or make feature requests at the [GitHub issue tracker](https://githu
 
 <hr style="color: #C0C0C0; background-color: #C0C0C0; border-color: #C0C0C0; height: 2px;" />
 <div style="float:right;">
-<a href="https://github.com/tomaswolf/gerrit-gitblit-plugin" target="_blank">GitBlit plugin 2.12.171.5-SNAPSHOT</a>
+<a href="https://github.com/tomaswolf/gerrit-gitblit-plugin" target="_blank">GitBlit plugin 2.12.171.6-SNAPSHOT</a>
 </div>
 <script type="text/javascript" src="version_check.js"></script>

pom.xml

@@ -20,7 +20,7 @@ limitations under the License.
   <artifactId>gitblit-plugin</artifactId>
   <description>GitBlit for Gerrit integrated as a plugin</description>
   <name>Gerrit - GitBlit Plugin</name>
-  <version>2.12.171.5-SNAPSHOT</version><!-- Gerrit API version followed by collapsed GitBlit version, followed by plugin version -->
+  <version>2.12.171.6-SNAPSHOT</version><!-- Gerrit API version followed by collapsed GitBlit version, followed by plugin version -->
   <licenses>
     <license>
       <name>Apache License 2.0</name>

src/main/java/com/gitblit/models/RefModel.java

@@ -59,9 +59,9 @@ public RefModel(String displayName, Ref ref, RevObject refObject) {
 		this.reference = ref;
 		this.displayName = displayName;
 		this.date = internalGetDate(refObject);
-		this.name = (ref != null) ? ref.getName() : displayName;
+		this.name = ref != null ? ref.getName() : displayName;
 		this.type = internalGetReferencedObjectType(refObject);
-		this.objectId = internalGetObjectId(reference);
+		this.objectId = ref != null ? ref.getObjectId() : ObjectId.zeroId();
 		this.id = this.objectId.getName();
 		this.referencedObjectId = internalGetReferencedObjectId(refObject);
 		this.referencedId = this.referencedObjectId.getName();
@@ -163,10 +163,6 @@ public PersonIdent getAuthorIdent() {
 		return person;
 	}
 
-	private ObjectId internalGetObjectId(Ref reference) {
-		return reference.getObjectId();
-	}
-
 	public ObjectId getObjectId() {
 		if (objectId == null) {
 			objectId = ObjectId.fromString(id);
@@ -178,7 +174,7 @@ private boolean internalIsAnnotatedTag(Ref reference, RevObject referencedObject
 		if (referencedObject instanceof RevTag) {
 			return !getReferencedObjectId().equals(getObjectId());
 		}
-		return reference.getPeeledObjectId() != null;
+		return reference != null && reference.getPeeledObjectId() != null;
 	}
 
 	public boolean isAnnotatedTag() {