Merge branch '5.2' into 5.3

* 5.2:
  Fix incompatible implicit float-to-int conversions
  [Translation] Don't pass null to strtoupper()
  cs fix
  [String] Fix implicit float-to-int casts
  [DependencyInjection] Don't pass null to trim()
  Add return types to JsonSerializable implementations
  Fix Serializable deprecations triggered by token mocks
  Add missing security translations

Dumper/PhpDumper.php

@@ -2224,7 +2224,9 @@ private function getClasses(Definition $definition, string $id): array
                 $classes[] = trim($tag['class'], '\\');
             }
 
-            $classes[] = trim($definition->getClass(), '\\');
+            if ($class = $definition->getClass()) {
+                $classes[] = trim($class, '\\');
+            }
             $factory = $definition->getFactory();
 
             if (!\is_array($factory)) {
@@ -2241,6 +2243,6 @@ private function getClasses(Definition $definition, string $id): array
             $definition = $factory[0];
         }
 
-        return array_filter($classes);
+        return $classes;
     }
 }