Dense SABR Params

Key _Dense SABR Params in Vol Curve refers to the set with the SABR dense parameters as returned by QuantLib, represented as an object of type Set
Always empty at the current implementation because of the setting ATM Calibrated = false

Note this key is prefixed by _, which indicates it is regarded as a read-only part of the object's data and therefore its associated value cannot be edited.
For that reason it does not appear as part of the input data.
It carries informational only value for the user and appears as part of its contents.
Also it completely depends on the remaining object contents and therefore is never part of the exported object's data.