discovered_networks in avi_pool causes an update on each plan/apply

[giovannibaratta]

Describe the bug

When creating a resource of type avi_pool, leaving the attribute discovered_networks in servers will produce a diff in subsequent plan/apply.

Reproduction steps

resource "avi_pool" "pool2" {
  name                = "additional-pool"
  cloud_ref           = var.cloud_id
  default_server_port = 8200
  health_monitor_refs = [avi_healthmonitor.hm.id]

  servers {
    ip {
      type = "V4"
      addr = "172.17.0.14"
    }
    hostname = "this-is-a-value"
  }

  ssl_profile_ref = avi_sslprofile.pool_profile.id
}

Result in this terraform diff

Terraform will perform the following actions:

  # module.vault_cluster.module.lb[0].avi_pool.pool2 will be updated in-place
  ~ resource "avi_pool" "pool2" {
        id                                    = "https://172.17.0.30/api/pool/pool-feafecc3-1b69-466f-91dd-c4d4c6d8c0a6"
        name                                  = "additional-pool"
        # (38 unchanged attributes hidden)

      ~ servers {
            # (7 unchanged attributes hidden)

          - discovered_networks {
              - network_ref = "https://172.17.0.30/api/network/dvportgroup-4033-cloud-746a7edc-7d79-49f4-bffb-c8cc2a05967b" -> null

              - subnet {
                  - mask = "16" -> null

                  - ip_addr {
                      - addr = "172.17.0.0" -> null
                      - type = "V4" -> null
                    }
                }
            }

            # (1 unchanged block hidden)
        }

        # (1 unchanged block hidden)
    }

Plan: 0 to add, 1 to change, 0 to destroy.

Expected behavior

Terraform should not generate any difference during subsequent plan/apply

Additional context

From my understanding discovered_networks should be an internal-use attribute and it should not even be proposed as an editable attribute in terraform. In this case, leaving the attribute unset will produce the diff posted above.