The keyed properties a record of extensions gives to a data source: the
keys whose value cannot be undefined as required readonly properties,
the keys whose value may be undefined as optional ones (without the
undefined). Nothing else: a key not in the record is not a property.
The extensions part of IDataSource.
The keyed properties a record of extensions gives to a data source: the keys whose value cannot be
undefinedas required readonly properties, the keys whose value may beundefinedas optional ones (without theundefined). Nothing else: a key not in the record is not a property. The extensions part of IDataSource.