The import of System features is not working as expected

[pavithran-rathinam]

Issue Details:
The System Profile Features properties are not being imported successfully. Rather than importing the expected field values, they are being overwritten or updated.

I have observed several recurring issues across the resource:

1. For properties with the type list, if there are no values defined, these properties are being updated to null. There should be no update for these properties during the import process.

Please refer to the examples provided below.

# module.sdwan.sdwan_system_snmp_feature.system_snmp_feature["system1-snmp"] will be updated in-place
# (imported from "a1e3002a-45c0-4c75-bc11-d1bd4dfcee81,08d43cbf-f5b0-420d-8a57-5b69e1325b58")
             ~ resource "sdwan_system_snmp_feature" "system_snmp_feature" {
             - communities         = [] -> null
                contact_person      = "person1"
     }

  # module.sdwan.sdwan_system_basic_feature.system_basic_feature["system2-basic"] will be updated in-place
  # (imported from "<id>")
  ~ resource "sdwan_system_basic_feature" "system_basic_feature" {
      - affinity_per_vrfs      = [] -> null
        feature_profile_id     = "<feature_profile_id>"
      - gps_sms_mobile_numbers = [] -> null
        id                     = "<id>"
        name                   = "basic"
      ~ version                = 0 -> (known after apply)
    }

2. Fields such as password, key_string, and key, which use $CRYPT and $CRYPT_CLUSTER encryption methods, are always being updated, even though the values are correctly generated in sdwan.json and the data/ model folder. Please review all fields that involve encryption and address this import issue.

  # module.sdwan.sdwan_system_aaa_feature.system_aaa_feature["system1-aaa"] will be updated in-place
  # (imported from "<id>")
  ~ resource "sdwan_system_aaa_feature" "system_aaa_feature" {
        accounting_group              = true
        description                   = "description"
        feature_profile_id            = "<feature_profile_id>"
        id                            = "<id>"
        name                          = "name_aaa_full"
      ~ radius_groups                 = [
          ~ {
                group_name                = "radius-grop"
              ~ servers                   = [
                  ~ {
                        acct_port  = 1012
                      + key        = "$CRYPT$sdkljhJKLasd"
                        timeout    = 200
                    },
                ]
            },
        ]
      ~ tacacs_groups                 = [
          ~ {
                group_name                = "group_name1"
              ~ servers                   = [
                  ~ {
                        address    = "10.1.1.1"
                      + key        = "$CRYPT$JKHASjasdkjasd2"
                        port       = 120
                        timeout    = 200
                    },
                ]
            },
        ]
      ~ users                         = [
          ~ {
                name        = "name"
              + password    = "$CRYPT$/gASKasSAIilasjdl"
              - public_keys = [] -> null
            },
          ~ {
                name        = "failsafe"
              + password    = "$CRYPT$jkhsKHsadLJlksad"
                privilege   = "15"
            },
        ]
      ~ version                       = 0 -> (known after apply)
    }

Here are a few affected Terraform resource; please review and add any others as necessary
sdwan_system_aaa_feature
sdwan_system_basic_feature
sdwan_system_bfd_feature
sdwan_system_logging_feature
sdwan_system_ntp_feature
sdwan_system_security_feature
sdwan_system_snmp_feature