code: public GridFSInputFile createFile(final InputStream in, final String filename, final boolean closeStreamOnPersist) {
          return new GridFSInputFile(this, in, filename, closeStreamOnPersist);
      }
docs: Creates a file entry. After calling this method, you have to call {@link com.mongodb.gridfs.GridFSInputFile#save()}.
  
  @param in                   an inputstream containing the file's data
  @param filename             the file name as stored in the db
  @param closeStreamOnPersist indicate the passed in input stream should be closed once the data chunk persisted
  @return a gridfs input file