Use template type for StateFactory methods to assist IDEs better.

changelog/rpp-add-template-type-create_state

@@ -0,0 +1,5 @@
+Significance: patch
+Type: dev
+Comment: Use template type for StateFactory methods to assist IDEs better.
+
+

src/Internal/Payment/State/AbstractPaymentState.php

@@ -103,8 +103,11 @@ public function complete_processing() {
 	 * This method should only be called whenever the process is ready to transition
 	 * to the next state, as each new state will be considered the payment's latest one.
 	 *
-	 * @param string $state_class The class of the state to crate.
-	 * @return AbstractPaymentState
+	 * @template ConcreteState
+	 * @param class-string<ConcreteState> | string $state_class The class of the state to crate.
+	 *
+	 * @return AbstractPaymentState | ConcreteState
+	 *
 	 * @throws StateTransitionException In case the new state could not be created.
 	 * @throws ContainerException       When the dependency container cannot instantiate the state.
 	 */

src/Internal/Payment/State/StateFactory.php

@@ -38,9 +38,11 @@ public function __construct( Container $container ) {
 	/**
 	 * Creates a new state based on class name.
 	 *
-	 * @param string         $state_class Name of the state class.
-	 * @param PaymentContext $context     Context for the new state.
-	 * @return AbstractPaymentState       The generated payment state instance.
+	 * @template ConcreteState
+	 * @param class-string<ConcreteState> | string $state_class Name of the state class.
+	 * @param PaymentContext                       $context     Context for the new state.
+	 *
+	 * @return AbstractPaymentState | ConcreteState                        The generated payment state instance.
 	 * @throws ContainerException         When the dependency container cannot instantiate the state.
 	 * @throws StateTransitionException   When the class name is not a state.
 	 */