[HttpFoundation] fixed return type of method HeaderBag::get

Author: AmsTaFFix

src/Symfony/Component/HttpFoundation/HeaderBag.php

@@ -101,11 +101,11 @@ public function add(array $headers)
     /**
      * Returns a header value by name.
      *
-     * @param string $key     The header name
-     * @param mixed  $default The default value
-     * @param bool   $first   Whether to return the first value or all header values
+     * @param string          $key     The header name
+     * @param string|string[] $default The default value
+     * @param bool            $first   Whether to return the first value or all header values
      *
-     * @return string|array The first header value if $first is true, an array of values otherwise
+     * @return string|string[] The first header value or default value if $first is true, an array of values otherwise
      */
     public function get($key, $default = null, $first = true)
     {
@@ -129,9 +129,9 @@ public function get($key, $default = null, $first = true)
     /**
      * Sets a header by name.
      *
-     * @param string       $key     The key
-     * @param string|array $values  The value or an array of values
-     * @param bool         $replace Whether to replace the actual value or not (true by default)
+     * @param string          $key     The key
+     * @param string|string[] $values  The value or an array of values
+     * @param bool            $replace Whether to replace the actual value or not (true by default)
      */
     public function set($key, $values, $replace = true)
     {