putIfAbsent abstract method
Associates the specified key
with the given value
if not already associated with a value.
key
: key with which the specified value is to be associatedvalue
: value to be associated with the specified keydelegate
: provides the caller a way of changing the CacheEntry before persistence
Returns true
if a value was set.
Implementation
@override
Future<bool> putIfAbsent(String key, T value,
{CacheEntryDelegate<T>? delegate});