title: Searching in Liferay document library by document extension
body: <p>I was developing a module for advanced search over liferay content, and I was stuck in document library search, it was asked to search in documents by document type, and I wish to know the feasibility of such feature, I've check liferay code and found that the document library indexer does not index the document extension instead it indexes the whole file name</p>
  
  <p>Kindly help me with this issue</p>