[PWA-2721] upward-php latest develop not compatible with php 7.4 on cloud pro. (#8)

* Remove types that don't support 7.4

* Code style fixes

* Add attribute until we drop support for 7.4

Author: tjwiebell

.gitignore

@@ -151,5 +151,6 @@ fabric.properties
 # End of https://www.gitignore.io/api/macos,linux,composer,phpstorm,visualstudiocode
 
 .php_cs.cache
+.php-cs-fixer.cache
 phpunit.xml
 node_modules

src/AbstractKeyValueStore.php

@@ -27,7 +27,8 @@ public function count(): int
         return \count($this->data);
     }
 
-    public function current(): mixed
+    #[\ReturnTypeWillChange]
+    public function current()
     {
         return $this->get($this->key());
     }
@@ -123,15 +124,14 @@ public function isList(): bool
 
     /**
      * Data to include when serializing to JSON.
-     *
-     * @return array
      */
-    public function jsonSerialize(): mixed
+    public function jsonSerialize(): array
     {
         return $this->toArray();
     }
 
-    public function key(): mixed
+    #[\ReturnTypeWillChange]
+    public function key()
     {
         return key($this->data);
     }

src/Controller.php

@@ -28,6 +28,8 @@ class Controller
     private $request;
 
     /**
+     * @param ?array $additionalResolvers
+     *
      * @throws \RuntimeException if a required key is missing from $upwardCofig file
      */
     public function __construct(

src/ResolverFactory.php

@@ -30,7 +30,7 @@ class ResolverFactory
         self::RESOLVER_TYPE_PROXY       => Resolver\Proxy::class,
         self::RESOLVER_TYPE_SERVICE     => Resolver\Service::class,
         self::RESOLVER_TYPE_TEMPLATE    => Resolver\Template::class,
-        self::RESOLVER_TYPE_URL         => Resolver\Url::class
+        self::RESOLVER_TYPE_URL         => Resolver\Url::class,
     ];
 
     /**