Configure the storage with the conflict_handling parameter value:
   0: (default): no resolution (ie, throw an Error)
   1: keep the local state
      (overwrites the remote document with local content)
      (delete remote document if local is deleted)
   2: keep the remote state
      (overwrites the local document with remote content)
      (delete local document if remote is deleted)
   3: keep both copies (leave documents untouched, no signature update)