[Openstack Heat] - Problems to find right Heat syntax to declare static route in a router template

From the OS::Neutron::Router resource description I guess this belongs into

Hi, I want extend my router HOT template by adding a static route. In the Openstack cli this would be openstack router add route --route destination='1.2.3.4/17',gateway='10.0.0.66' myrouter the value_specs section as a map, but all my attempts failed, e.g. router1: type: 'OS::Neutron::Router' properties: external_gateway_info: network: provider name: myrouter value_specs: route: destination: '0.0.0.0/0' gateway: '10.0.0.62' Can somebody help me with the correct syntax? Thanks & best regards, Dieter