Updated more docblocks

src/League/OAuth2/Server/Grant/Password.php

@@ -94,7 +94,8 @@ class Password implements GrantTypeInterface {
 
     /**
      * Set the callback to verify a user's username and password
-     * @param function $callback The callback function
+     * @param callable $callback The callback function
+     * @return void
      */
     public function setVerifyCredentialsCallback($callback)
     {
@@ -103,7 +104,7 @@ class Password implements GrantTypeInterface {
 
     /**
      * Return the callback function
-     * @return function
+     * @return callable
      */
     protected function getVerifyCredentialsCallback()
     {

src/League/OAuth2/Server/Grant/RefreshToken.php

@@ -56,7 +56,7 @@ class RefreshToken implements GrantTypeInterface {
 
     /**
      * Constructor
-     * @param AuthServer $authServer AuthServer instance
+     * @param Authorization $authServer Authorization server instance
      * @return void
      */
     public function __construct(Authorization $authServer)