Difficulties using jump host, ssh demands for password of unexpected user

I took inspiration from the FAQ which describes how to use jump hosts / ssh proxies in combination with ansible playbooks.

In order to connect to servers I have to use a syntax like this:
ssh myuser@technicaluser@targethost@jumphost
This works fine on all of my machines and also on that where I run ansible from. I only need to enter the password of myuser which is just fine.

To get ansible working I created an inventory file called inventory with this content:
[category]
targethost ansible_user=myuser

In the host_vars of targethost I have
ansible_ssh_common_args: ‘-o ProxyCommand=“ssh -vvvv -W %h:%p technicaluser@jumphost”’

Then I run
ansible -i inventory category -m ping

But in contrast to the regular ssh command I am being asked for the password of the technical user
technicaluser@jumphost’s password:

The problem with this is that by design I do not know the password of the technical user and therefore I am lost.

Where is my mistake ?
I am on Ansible 2.4.2.0, OpenSSH 7.4p1 and CentOS 7.4.1708