Merge branch '6.0' into 6.1

* 6.0:
  ignore the cached body when comparing e-mails for equality
  fix PHP syntax to be compatible with 7.2 and 7.3
  [HttpFoundation] Add session ID regex comment
  [Workflow] Fix typo in MethodMarkingStore
  Fix CS

Author: fabpot

Email.php

@@ -477,9 +477,7 @@ private function generateBody(): AbstractPart
             }
         }
 
-        $this->cachedBody = $part;
-
-        return $part;
+        return $this->cachedBody = $part;
     }
 
     private function prepareParts(): ?array

Tests/MessageConverterTest.php

@@ -75,6 +75,12 @@ private function assertConversion(Email $expected)
             $expected->html('HTML content');
             $converted->html('HTML content');
         }
+
+        $r = new \ReflectionProperty($expected, 'cachedBody');
+        $r->setAccessible(true);
+        $r->setValue($expected, null);
+        $r->setValue($converted, null);
+
         $this->assertEquals($expected, $converted);
     }
 }