getOrPut
Retrieves the value associated with the specified key if it exists. If the key does not already have an associated value, the result of invoking the defaultValue function will be stored and returned as the value for the given key.
Return
the value associated with the key, either retrieved from the existing association or newly computed and stored.
Parameters
key
the dependency key used to look up or store the value.
defaultValue
a lambda function that provides a default value to store and return if the key is not found.