query
  Deprecated in Select2 4.0. This has been replaced by another option and is only available in the full builds of Select2.
    In the past, Select2 supported an option called query that
    allowed for a custom data source to be used. This option has been replaced
    by the query method on the
    data adapter and takes a very similar set of
    parameters.
  
query
        params (including a callback)
        DataAdapter
        Query