$jd = 'jdjd/test.xml';
$jdSlash = rawurlencode('jdjd/test.xml');
$jnSlash = rawurlencode('jn%2Fjn/test.xml');
$jn = 'jn%2Fjn/test.xml';
var_dump($jd); // string(13) "jdjd/test.xml"
var_dump(simplexml_load_file($jd)); // OK object(SimpleXMLElement) 
var_dump($jdSlash); // string(15) "jdjd%2Ftest.xml"
var_dump(simplexml_load_file($jdSlash)); // OK object(SimpleXMLElement) 
var_dump($jnSlash); // string(20) "jn%252Fjn%2Ftest.xml"
var_dump(simplexml_load_file($jnSlash)); // OK object(SimpleXMLElement)
var_dump($jn); // string(16) "jn%2Fjn/test.xml"
var_dump(simplexml_load_file($jn)); // PHP Warning: simplexml_load_file(): I/O warning : failed to load external entity "jn%2Fjn/test.xml"

$xml = @simplexml_load_string(file_get_contents($this->containerXml));