"url" query parameter causes conflict in FHIR ValueSet $expand endpoint

[ander-chan]

Steps to Reproduce :

Call the $expand endpoint with a url param, containing a fragment identifier, for example:

GET /ValueSet/$expand?url=http://example.org
GET /ValueSet/$expand?url=#code

Observe that the REST layer fails to handle the #code fragment correctly.

Instead of returning the expanded ValueSet including the fragment-specific "opeation", the server may return an error, an empty expansion, or unexpected results.

Expected Behavior:

The $expand endpoint (as param) should correctly interpret the full $url query param, including any fragment identifier (e.g., #code), and return the corresponding expanded concepts.
$url param php must by "http://example.org" or "#code"

Actual Behavior :

• $url param with # identifiers result in errors.
• Full $url param (with a http.. value) may be misinterpreted inside the REST layer, causing incorrect value of $url parameter.

<?php
use Luracast\Restler\RestException;

class ValueSet
{
    /**
     * @url GET /{$operator}
     * @param string $expand 
     * @param string $url Resource URL of the ValueSet
     * @param string $_format Resource URL of the ValueSet
     * @param string $_count Resource URL of the ValueSet
     */
    public function index($operator=null,$url = null,$_count=null)
    {
    	$refer = '';
	if(isset($_SERVER['HTTP_REFERER'])) $refer = $_SERVER['HTTP_REFERER'];
	
        $valuesets = json_decode(file_get_contents(__DIR__ . '/valuesets.json'), true);
        
       

	if (!str_contains($operator, '$')) {
	   $code = $operator;
	   foreach($valuesets as $vs)       
       	  if(isset($vs["id"]) && $vs["id"] === $code) return $vs;
       	   throw new RestException(404, "ValueSet not found: code=" . $code);
	} 
        	
//       	$url = explode('?url=',$url)[1];
       $contains =[];
       
       foreach($valuesets as $vs) 
       	foreach($vs["expansion"]["contains"] as $item)
       	  isset($item["system"]) && $item["system"] === $url && $contains[]=$item;
      
	return [
	    "resourceType" => "ValueSet",
	    "url" => $refer,
	    "status" => "active",
	    "expansion" => [
		"timestamp" => date(DATE_ATOM),
		"total" => count($contains),
		"contains" => $contains
	    ]
	];
    }
...