twig: Handle dash in JSON

If JSON contains some dashes (“-“) in the keys, the usual way of twig does not work. Here you finde how to solve this: JSON:

twig-code for plugin template manager:
id: {{id}}
mvalue: {{attributes.mvalue}}
test-value: {{attributes.test-value}}
test-value: {{ attribute(attributes, 'test-value') }}

[jsoncontentimporterpro url= id=ID_TEMPLATE_MANAGER]

In Action:
id: 327456
mvalue: 543543.067567575
test-value: 0
test-value: 2352.07597459064