Yang validation fails when Buffer profiles are configured with "NULL" values

[dgsudharsan]

Description

Below is the sample buffer configuration. In dynamic buffer model, "NULL" is a legal value but yang model check doesn't tolerance it.

Failed to install p4-examples=1.0.1-8: Failed to install p4-examples: Data Loading Failed
Leafref "/sonic-buffer-profile:sonic-buffer-profile/sonic-buffer-profile:BUFFER_PROFILE/sonic-buffer-profile:BUFFER_PROFILE_LIST/sonic-buffer-profile:name" of value "NULL" points to a non-existing leaf.

"BUFFER_PG": {
    "Ethernet0|0": {
        "profile": "ingress_lossy_profile"
    },
    "Ethernet0|3-4": {
        "profile": "NULL"
    }

}

Issue is from the below yang model where the value can be only a leafref and so having NULL fails. We also need to check other yang models where buffer profile can be NULL

https://github.com/Azure/sonic-buildimage/blob/7eb321c376fd1fcdbc67462185b8d4a7cff5f76f/src/sonic-yang-models/yang-models/sonic-buffer-pg.yang#L58

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[zhangyanzhao]

@adyeung Adam, can you please help to find someone in BRCM to take a look? Thanks.

[adyeung]

@AmitKaushik7 Amit from BRCM will followup

[AmitKaushik7]

Raised a PR #10353 [Allow NULL Buffer Profile in buffer pg/queue yang files for Dynamic Buffer Model ] for this issue.