Improve some PHPdocs based on existing Symfony stubs in PHPstan and Psalm

Author: mdeboer

Envelope.php

@@ -21,7 +21,7 @@
 final class Envelope
 {
     /**
-     * @var array<string, list<StampInterface>>
+     * @var array<class-string<StampInterface>, list<StampInterface>>
      */
     private array $stamps = [];
     private object $message;
@@ -106,7 +106,13 @@ public function last(string $stampFqcn): ?StampInterface
     }
 
     /**
+     * @template TStamp of StampInterface
+     *
+     * @param class-string<TStamp>|null $stampFqcn
+     *
      * @return StampInterface[]|StampInterface[][] The stamps for the specified FQCN, or all stamps by their class name
+     *
+     * @psalm-return ($stampFqcn is string : array<class-string<StampInterface>, list<StampInterface>> ? list<TStamp>)
      */
     public function all(string $stampFqcn = null): array
     {