DependenciesStrategy enum Null safety
How should precondition handle it's dependencies.
- stayInSuccessCache → const DependenciesStrategy
Once resolved to "success", precondition will stay in success state for Precondition.satisfiedCache duration, and it will not attempt to evaluate it's dependencies.
- unsatisfiedOnUnsatisfied → const DependenciesStrategy
Successful Precondition will always evaluate it's dependencies and regardless of its cache settings: it becomes unsatisfied if dependencies are not unsatisfied.