 
     indexes           :
       identifier      : 'unique'
+      fields          : 'sparse'
 
     schema            :
 

      credData.save (err) ->
        return  if failed err, callback

        { identifier } = credData
        credential = new JCredential { provider, title, identifier, originId }

        credential.save (err) ->
          return  if failed err, callback, credData


      meta            : require 'bongo/bundles/meta'

      fields          :
        type          : [String]
        default       : -> []

      verified        :
        type          : Boolean
        default       : -> no
