"show interfaces neighbor expected" returns empty results when neighbor missing loopback address

[veronica-arista]

Description

"show interfaces neighbor expected" returns empty results when run on our clusters after a recent change in minigraph.py:
1496d1d

Specifically, the device_data now explicitly excludes values that are "None", resulting in the entry being skipped by the "show interfaces neighbor expected" command implementation ( show/interfaces/__init__.py )

Steps to reproduce the issue:

1. Run "show interfaces neighbor expected" on a DUT for which the neighbor metadata lacks loopback addr

Describe the results you received:

The command now returns empty results, though our device has neighbors:

root@nfc420-7:~# show interfaces neighbor expected
LocalPort    Neighbor    NeighborPort    NeighborLoopback    NeighborMgmt    NeighborType
-----------  ----------  --------------  ------------------  --------------  --------------

root@nfc420-7:~# sonic-cfggen -d --var-json "DEVICE_NEIGHBOR"
{
    "Ethernet0": {
        "name": "ARISTA01T3",
        "port": "Ethernet1"
    },
    "Ethernet160": {
        "name": "ARISTA03T3",
        "port": "Ethernet1"
    },
    "Ethernet168": {
        "name": "ARISTA04T3",
        "port": "Ethernet1"
    },
    "Ethernet172": {
        "name": "ARISTA04T3",
        "port": "Ethernet2"
    },
    "Ethernet176": {
        "name": "ARISTA06T3",
        "port": "Ethernet1"
    },
    "Ethernet36": {
        "name": "ARISTA01T3",
        "port": "Ethernet2"
    }
}

Describe the results you expected:

Prior to the change in minigraph.py the command returned the following on the same device:

root@nfc420-7:~$ show interfaces neighbor expected
LocalPort    Neighbor    NeighborPort    NeighborLoopback    NeighborMgmt    NeighborType
-----------  ----------  --------------  ------------------  --------------  --------------
Ethernet0    ARISTA01T3  Ethernet1       None                10.250.25.2     CoreRouter
Ethernet36   ARISTA01T3  Ethernet2       None                10.250.25.2     CoreRouter
Ethernet160  ARISTA03T3  Ethernet1       None                10.250.25.3     CoreRouter
Ethernet168  ARISTA04T3  Ethernet1       None                10.250.25.4     CoreRouter
Ethernet172  ARISTA04T3  Ethernet2       None                10.250.25.4     CoreRouter
Ethernet176  ARISTA06T3  Ethernet1       None                10.250.25.5     CoreRouter

Output of show version:

Output of show techsupport:

Additional information you deem important (e.g. issue happens only occasionally):

[judyjoseph]

@jcaiMR Could you check why it is getting skipped in show command. Thanks.

[wenyiz2021]

this issue should be fixed by sonic-net/sonic-utilities#2465
it is already in 202205
it adds safety check if lo_addr etc is emtpy