How should be a multi-source item handled.

Item Summary
Name	Type	Multiplicity	Description
defaultAuthoritativeSource	container ObjectTemplateMappingType	[0,1]	A mapping that takes existing identity data and provides a value for `identities/defaultAuthoritativeSource` property.

Items
- defaultAuthoritativeSource
  
  Flags: RAM,runtime
  
  Multiplicity: [0,1]
  
  A mapping that takes existing identity data and provides a value for `identities/defaultAuthoritativeSource` property. It has a default strength of `strong`, and a default source of `identities/identity`.