GetPolicyChecker returns instances of PolicyChecker; the actual implementation is controlled by the factory that is registered via RegisterPolicyCheckerFactory.

NewPolicyChecker creates a new instance of PolicyChecker.

RegisterPolicyCheckerFactory is to be called once to set the factory that will be used to obtain instances of PolicyChecker.

PolicyChecker offers methods to check a signed proposal against a specific policy defined in a channel or not.

PolicyCheckerFactory defines a factory interface so that the actual implementation can be injected.