Merge branch '6.1' into 6.2

* 6.1:
  Update ComposerPlugin.php
  [Notifier] [OvhCloud] handle invalid receiver
  [Cache] fix collecting cache stats when nesting computations
  [VarDumper] Fix JS to expand / collapse
  [Validator] Fix Email validator logic
  Fix user_identifier support after username has been deprecated in favor of it.
  [Tests] Remove `$this` occurrences in future static data providers
  [PropertyInfo] Fixes constructor extractor for mixed type
  use method_exists() instead of catching reflection exceptions

Author: nicolas-grekas

Tests/ExpressionLanguageTest.php

@@ -121,8 +121,19 @@ public function testParseThrowsInsteadOfNotice()
 
     public function shortCircuitProviderEvaluate()
     {
-        $object = $this->getMockBuilder(\stdClass::class)->setMethods(['foo'])->getMock();
-        $object->expects($this->never())->method('foo');
+        $object = new class(\Closure::fromCallable([static::class, 'fail'])) {
+            private $fail;
+
+            public function __construct(callable $fail)
+            {
+                $this->fail = $fail;
+            }
+
+            public function foo()
+            {
+                ($this->fail)();
+            }
+        };
 
         return [
             ['false and object.foo()', ['object' => $object], false],