Updates the value of the node at the given path to value.
In order for this method to work, the node provider must be mutable.
If you did not specify a custom node provider, the created provider is mutable.
Source
void updateValue(String path, dynamic value) {
if (provider is! MutableNodeProvider) {
throw new Exception("Unable to Modify Node Provider: It is not mutable.");
}
(provider as MutableNodeProvider).updateValue(path, value);
}