Again $GET and $_POST

I am running Drupal 8.2.4

I created a node (page) with PHP text format, say node/999:

$getHttpHost= \Drupal::request()->getHttpHost();
echo("getHttpHost=[".$getHttpHost."]<br>");

$getClientIp= \Drupal::request()->getClientIp();
echo("getClientIp=[".$getClientIp."]<br>");

$getScriptName= \Drupal::request()->getScriptName();
echo("getScriptName=[".$getScriptName."]<br>");

When I try http://mysite.ca/node/999
I get host, IP and script as expected.

When I try

$getRequestUri= \Drupal::request()->getRequestUri();
echo("getRequestUri=[".$getRequestUri."]<br>");

$getQueryString= \Drupal::request()->getQueryString();
echo("getQueryString=[".$getQueryString."]<br>");

$query = \Drupal::request()->query->all();
echo("query=[");
print_r($query );
echo("]<br>");
echo("<br>");

$request= \Drupal::request()->request->all();
echo("request=[");
print_r($request);
echo("]<br>");
echo("<br>");

and point the browser to
http://mysite.ca/node/999?par1=val1&par2=val2

I get:

getRequestUri=[/node/999]
getQueryString=[]

query=[Array ( ) ]

request=[Array ( ) ]

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Why cannot I get $_GET parameters?

Thank you.