The originalSpec is validated as an index specification but there's no requirement the originalSpec has any association with the actual index definition. Some examples of validation which are absent and may lead to problematic behavior if assumptions change in the future include:

• The originalSpec option can be specified for a non-timeseries collection.
• The originalSpec option can be an index specification with its own nested originalSpec option.
• The index specification's name and version are not required to match originalSpec.name or originalSpec.v, respectively.
• The originalSpec option can refer to an index specification which will be returned by listIndexes yet errors when provided to createIndexes.