code: func ParseLegacyExporter(legacyExporter string, legacyExporterOpts []string) ([]client.ExportEntry, error) {
  	var ex client.ExportEntry
  	ex.Type = legacyExporter
  	var err error
  	ex.Attrs, err = attrMap(legacyExporterOpts)
  	if err != nil {
  		return nil, errors.Wrap(err, "invalid exporter-opt")
  	}
  	if v, ok := ex.Attrs["dest"]; ok {
  		return nil, errors.Errorf("dest=%s not supported for --exporter-opt, you meant output=%s?", v, v)
  	}
  	ex.Output, ex.OutputDir, err = resolveExporterDest(ex.Type, ex.Attrs["output"])
  	if err != nil {
  		return nil, errors.Wrap(err, "invalid exporter option: output")
  	}
  	if ex.Output != nil || ex.OutputDir != "" {
  		delete(ex.Attrs, "output")
  	}
  	return []client.ExportEntry{ex}, nil
  }
docs: // ParseLegacyExporter parses legacy --exporter <type> --exporter-opt <opt>=<optval>