Fixes #256: removed misleading line from phpdoc [skip ci]

Author: samdark

src/StateStorageInterface.php

@@ -30,7 +30,6 @@ public function set($key, $value);
 
     /**
      * Returns the state variable value with the variable name.
-     * If the variable does not exist, the `$defaultValue` will be returned.
      * @param string $key the variable name
      * @return mixed the variable value, or `null` if the variable does not exist.
      */
@@ -42,4 +41,4 @@ public function get($key);
      * @return bool success.
      */
     public function remove($key);
-}
+}