how to update document with DIH (FileDataSource)

Hi, all I am trying to index from both DB and file. and informations from DB and file make one document. so I decided update document which I have already indexed from DB. I will use DIH because of millions of files if I find how to update document with DIH. I need your help. Thanks in advance.

solrj sample code for solrcloud

Does anyone have solrj indexing and searching sample code? I could not find it on the internet. Thanks.