diff --git a/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit6/TestCompatibilityTrait.php b/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit6/TestCompatibilityTrait.php
index 0521d766d4..75e2d260d4 100644
--- a/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit6/TestCompatibilityTrait.php
+++ b/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit6/TestCompatibilityTrait.php
@@ -84,154 +84,154 @@ public static function assertNotEqualsCanonicalizing($expected, $actual, $messag
   /**
    * Forward compatibility for assertIsArray.
    */
-  public static function assertIsArray($actual, string $message = ''): void {
+  public static function assertIsArray($actual, $message = '') {
     static::assertInternalType('array', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsBool.
    */
-  public static function assertIsBool($actual, string $message = ''): void {
+  public static function assertIsBool($actual, $message = '') {
     static::assertInternalType('bool', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsFloat.
    */
-  public static function assertIsFloat($actual, string $message = ''): void {
+  public static function assertIsFloat($actual, $message = '') {
     static::assertInternalType('float', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsObject.
    */
-  public static function assertIsInt($actual, string $message = ''): void {
+  public static function assertIsInt($actual, $message = '') {
     static::assertInternalType('int', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsNumeric.
    */
-  public static function assertIsNumeric($actual, string $message = ''): void {
+  public static function assertIsNumeric($actual, $message = '') {
     static::assertInternalType('numeric', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsObject.
    */
-  public static function assertIsObject($actual, string $message = ''): void {
+  public static function assertIsObject($actual, $message = '') {
     static::assertInternalType('object', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsResource.
    */
-  public static function assertIsResource($actual, string $message = ''): void {
+  public static function assertIsResource($actual, $message = '') {
     static::assertInternalType('resource', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsString.
    */
-  public static function assertIsString($actual, string $message = ''): void {
+  public static function assertIsString($actual, $message = '') {
     static::assertInternalType('string', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsScalar.
    */
-  public static function assertIsScalar($actual, string $message = ''): void {
+  public static function assertIsScalar($actual, $message = '') {
     static::assertInternalType('scalar', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsCallable.
    */
-  public static function assertIsCallable($actual, string $message = ''): void {
+  public static function assertIsCallable($actual, $message = '') {
     static::assertInternalType('callable', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsIterable.
    */
-  public static function assertIsIterable($actual, string $message = ''): void {
+  public static function assertIsIterable($actual, $message = '') {
     static::assertTrue(\is_iterable($actual), $message);
   }
 
   /**
    * Forward compatibility for assertIsNotArray.
    */
-  public static function assertIsNotArray($actual, string $message = ''): void {
+  public static function assertIsNotArray($actual, $message = '') {
     static::assertNotInternalType('array', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsNotBool.
    */
-  public static function assertIsNotBool($actual, string $message = ''): void {
+  public static function assertIsNotBool($actual, $message = '') {
     static::assertNotInternalType('bool', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsNotFloat.
    */
-  public static function assertIsNotFloat($actual, string $message = ''): void {
+  public static function assertIsNotFloat($actual, $message = '') {
     static::assertNotInternalType('float', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsNotObject.
    */
-  public static function assertIsNotInt($actual, string $message = ''): void {
+  public static function assertIsNotInt($actual, $message = '') {
     static::assertNotInternalType('int', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsNotNumeric.
    */
-  public static function assertIsNotNumeric($actual, string $message = ''): void {
+  public static function assertIsNotNumeric($actual, $message = '') {
     static::assertNotInternalType('numeric', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsNotObject.
    */
-  public static function assertIsNotObject($actual, string $message = ''): void {
+  public static function assertIsNotObject($actual, $message = '') {
     static::assertNotInternalType('object', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsNotResource.
    */
-  public static function assertIsNotResource($actual, string $message = ''): void {
+  public static function assertIsNotResource($actual, $message = '') {
     static::assertNotInternalType('resource', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsNotString.
    */
-  public static function assertIsNotString($actual, string $message = ''): void {
+  public static function assertIsNotString($actual, $message = '') {
     static::assertNotInternalType('string', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsNotScalar.
    */
-  public static function assertIsNotScalar($actual, string $message = ''): void {
+  public static function assertIsNotScalar($actual, $message = '') {
     static::assertNotInternalType('scalar', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsNotCallable.
    */
-  public static function assertIsNotCallable($actual, string $message = ''): void {
+  public static function assertIsNotCallable($actual, $message = '') {
     static::assertNotInternalType('callable', $actual, $message);
   }
 
   /**
    * Forward compatibility for assertIsNotIterable.
    */
-  public static function assertIsNotIterable($actual, string $message = ''): void {
+  public static function assertIsNotIterable($actual, $message = '') {
     static::assertFalse(\is_iterable($actual), $message);
   }