operator [] method
Return Iterable of values for specified key
.
If no value associated with key then returns empty Iterable. If key not found then returns null.
Throws ArgumentError if key
is empty or null.
Throws ArgumentError if keyMapping(
key
)
is empty or null.
Implementation
@override
Set<V>? operator [](String key) {
final result = super[key];
return identical(result, null) ? null : result as Set<V>;
}