Whether to pass notMerge: true to setOption.
The option to pass to setOption. May differ from the input when normalisation is needed.
Component keys to pass as replaceMerge to setOption.
Empty array means no targeted replacement needed.
The signature of the normalised option.
Store this and pass it as prevSignature on the next call.
The result of optionMergePlan, a merge strategy plus the (possibly normalised) option to pass to
setOption.