The use of List<Option> to ImmutableArray<Option>, this prevents any unintended mutation of the options, and makes it clear to the code reader that these options are not mutated.
The use of Dictionary to ImmutableDictionary as well, for the same reason.
This changes two things:
List<Option>toImmutableArray<Option>, this prevents any unintended mutation of the options, and makes it clear to the code reader that these options are not mutated.DictionarytoImmutableDictionaryas well, for the same reason.