putAllAndUpdateExisting abstract method

Future<void> putAllAndUpdateExisting(
  1. Map<TKey, TVal> newValues,
  2. void mutateExisting(
    1. TKey key,
    2. TVal mutateMe,
    3. TVal newValueReadOnly
    )
)

Same as putAll, but instead of removing old objects, changes (mutates) their values to new values

Implementation

Future<void> putAllAndUpdateExisting(
  Map<TKey, TVal> newValues,
  void Function(TKey key, TVal mutateMe, TVal newValueReadOnly)
      mutateExisting,
);