阻止json_encode将空字符串编码为null

Is it possible for the PHP json_encode function do not convert empty string values to null?

UPDATE
I can not replicate this behaviour in clear conditions, and looks like it's already a default for this function.

This is already the default behavior.

json_encode(['test' => '']);

generates:

{"test":""}

No that i know of, but you could do this:

array_walk_recursive($value, function (&$item, $key) {
    $item = null === $item ? '' : $item;
});