Description of problem:

Playing around with linux-bridges and vlan filtering functionality with iproute command 'bridge' we found that it outputs a invalid json and that's a problemn for our processing tools.





rpm version: iproute-4.18.0-11.el8.x86_64
os: Red Hat Enterprise Linux CoreOS release 4.1
[core@test-1-mfqwp-master-0 ~]$ rpm-ostree status 
State: idle
AutomaticUpdates: disabled
Deployments:
* pivot://quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:fb025ff2b405cf5902a451675cd27a9d702ced7c88b5a33280d42069524874c6
              CustomOrigin: Managed by pivot tool
                   Version: 410.8.20190904.0 (2019-09-04T20:31:27Z)

  pivot://quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:53389c9b4a00d7afebb98f7bd9d20348deb1d77ca4baf194f0ae1b582b7e965b
              CustomOrigin: Provisioned from oscontainer
                   Version: 410.8.20190520.0 (2019-05-20T22:55:04Z)

How reproducible:


[root@bed1c2009bd8 /]# ip link add br0 type bridge
[root@bed1c2009bd8 /]# ip link set br0 up
[root@bed1c2009bd8 /]# ip link set br0 type bridge vlan_filtering 1
[root@bed1c2009bd8 /]# bridge vlan show 
port	vlan ids
br0
	 1 PVID untagged


Actual results:

[root@bed1c2009bd8 /]# bridge -j vlan show 
["br0","vlan":[{"vlan":1,"pvid":null,"untagged":null}]]


Expected results:

The correct output format need structs to be with brackets:
["br0",{"vlan":[{"vlan":1,"pvid":null,"untagged":null}]}]


Additional info:

Also same thing at centos:7 has better output, since network interfaces are struct fields too:

```
[root@69aabb0f165e /]# bridge vlan show 
port	vlan ids
br0	 1 PVID Egress Untagged

[root@69aabb0f165e /]# bridge -j vlan show 
{
    "br0": [{
            "vlan": 1,
            "flags": ["PVID","Egress Untagged"
            ]
        }
    ]
}
```