cakePHP returning empty parameters on the GET request

I'm having problem to read parameters on the GET request: www.example.com/users/checkusername?username=e

I'm using cakePHP 3, on cakePHP 2.6.4 is working without problem.

By these way I have an empty result:

$this->log($this->request->query['username']);
$this->log( $this->params['url']);

Result:

2015-04-28 17:28:22 Error:
2015-04-28 17:28:22 Error:

However, checking the whole request it's possible to verify that the parameter is there

$this->log($this->request);

These is the output:

2015-04-28 17:28:22 Error: Cake\Network\Request Object
(
    [params] => Array
        (
            [plugin] => 
            [controller] => Users
            [action] => checkusername
            [_ext] => 
            [pass] => Array
                (
                )

            [_Token] => Array
                (
                    [unlockedFields] => Array
                        (
                        )

                )

        )

    [data] => Array
        (
        )

    [query] => Array
        (
        )

    [cookies] => Array
        (
            [CAKEPHP] => u8lgs1cup81331lka3a90jidd4
        )

    [_environment:protected] => Array
        (
        **removed**
            [REQUEST_METHOD] => GET
            [REQUEST_URI] => /users/checkusername?username=e
            [SCRIPT_NAME] => /index.php
        **removed**
        )

    [url] => users/checkusername
    [base] => 
    [webroot] => /
    [here] => /users/checkusername
    [trustProxy] => 
    [_detectorCache:protected] => Array
        (
            [post] => 
            [put] => 
        )

    [_input:protected] => 
    [_session:protected] => Cake\Network\Session Object
        (
            [_engine:protected] => 
            [_started:protected] => 1
            [_lifetime:protected] => 1440
            [_isCli:protected] => 
        )

)

Does somebody have any idea how to read this parameter?

After more debugging

I found that the problem is related to the Hiawatha rewrite rule. I just add

<?php echo phpinfo(); ?>

at begining of the file /webroot/index.php.

When I use: https://www.example.com/?code=123

It works and I get these results

PHP Variables            Variable Value
_REQUEST["code"]           123
_GET["code"]               123
_SERVER["REQUEST_URI"]     /?code=123
_SERVER["SCRIPT_NAME"]     /index.php

But when I try: https://www.example.com/users/confirm?code=123

The variables are not showing.

_SERVER["REQUEST_URI"]     /users/confirm/?code=123
_SERVER["SCRIPT_NAME"]     /index.php

My rewrite rule is according recommendation on cakePHP book:

UrlToolkit {
   ToolkitID = cakephp
   RequestURI exists Return
   Match .* Rewrite /index.php
}

Does anyone have the rewrite rule for cakePHP or there is somewhere else to define it?

At the end is always simple

This is the rewrite rule for cakePHP on Hiawatha server receive GET request

UrlToolkit {
   ToolkitID = cakephp
   RequestURI exists Return
   Match .*\?(.*) Rewrite /index.php?$1
   Match .* Rewrite /index.php
}