/**
  * {@inheritDoc}
  *
  * @see Object#equals(Object)
  */
 @Override
 public boolean equals(Object obj) {
   if (this == obj) {
     return true;
   }
   if (obj == null) {
     return false;
   }
   if (!(obj instanceof AttachmentReference)) {
     return false;
   }
   AttachmentReference other = (AttachmentReference) obj;
   return StringUtils.areEqual(getFileName(), other.getFileName()) && wikiPageReference == null
       ? other.wikiPageReference == null
       : wikiPageReference.equals(other.wikiPageReference);
 }