Shorter way to write a Spread Operator in a array for null value

[Ronan-Lenor]

Description

add a new writing possibility, so that :

$array = [...($var !== null) ? ['key' => $var] : []];

could be shortened to

$array = ['key' ?=> $var];

So , if $var = null; then $array would result to []
and if $var = false; then $array would result to['key' => false]

( same as using an array_merge() + array_filter() )