Cannot override osapi_max_limit in heat templates via nova::config::nova_config

Issue

Trying to configure osapi_max_limit for nova controllers using heat:

ControllerExtraConfig:
    nova::config::nova_config:
        DEFAULT/osapi_max_limit:
            value: 5000

This doesn't work as it seems the variable is already defined in /usr/share/openstack-puppet/modules/nova/manifests/api.pp

nova_config {
'wsgi/api_paste_config': value => $api_paste_config;
'DEFAULT/enabled_apis': value => join($enabled_apis_real, ',');
'DEFAULT/osapi_compute_listen': value => $api_bind_address;
'DEFAULT/metadata_listen': value => $metadata_listen;

'DEFAULT/osapi_max_limit': value => $osapi_max_limit;
'DEFAULT/osapi_compute_link_prefix': value => $osapi_compute_link_prefix;
'DEFAULT/osapi_glance_link_prefix': value => $osapi_glance_link_prefix;
'DEFAULT/osapi_hide_server_address_states': value => $osapi_hide_server_address_states;
'DEFAULT/allow_instance_snapshots': value => $allow_instance_snapshots;
'DEFAULT/enable_network_quota': value => $enable_network_quota;
'DEFAULT/enable_instance_password': value => $enable_instance_password;
'DEFAULT/password_length': value => $password_length;
}

If deployment is run, the following error appears on the destination controller:

messages:Oct 2 15:19:06 ie2-lab-ctrl0 os-collect-config: #033[1;31mError: Duplicate declaration: Nova_config[DEFAULT/osapi_max_limit] is already declared; cannot redeclare at /etc/puppet/modules/nova/manifests/api.pp:477 on node ie2-lab-ctrl0.lab.mydomain#033[0m