Merge branch '4.4' into 5.1

* 4.4:
  Bump license year
  [Form] fix passing null $pattern to IntlDateFormatter
  Update README.md

Author: fabpot

DateFormatter/IntlDateFormatter.php

@@ -145,6 +145,10 @@ public function __construct(?string $locale, ?int $datetype, ?int $timetype, $ti
         $this->datetype = null !== $datetype ? $datetype : self::FULL;
         $this->timetype = null !== $timetype ? $timetype : self::FULL;
 
+        if ('' === ($pattern ?? '')) {
+            $pattern = $this->getDefaultPattern();
+        }
+
         $this->setPattern($pattern);
         $this->setTimeZone($timezone);
     }
@@ -484,7 +488,7 @@ public function setLenient(bool $lenient)
     /**
      * Set the formatter's pattern.
      *
-     * @param string|null $pattern A pattern string in conformance with the ICU IntlDateFormatter documentation
+     * @param string $pattern A pattern string in conformance with the ICU IntlDateFormatter documentation
      *
      * @return bool true on success or false on failure
      *
@@ -493,11 +497,7 @@ public function setLenient(bool $lenient)
      */
     public function setPattern(?string $pattern)
     {
-        if (null === $pattern) {
-            $pattern = $this->getDefaultPattern();
-        }
-
-        $this->pattern = $pattern;
+        $this->pattern = (string) $pattern;
 
         return true;
     }

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2004-2020 Fabien Potencier
+Copyright (c) 2004-2021 Fabien Potencier
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal