New-AzApiManagementBackend 4.0.5 fails with "'url' should not be empty"

### Description

When using Az.ApiManagement 4.0.5, `New-AzApiManagementBackend` command fails even when parameters are provided.
```
New-AzApiManagementBackend `
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| Error Code: ValidationError Error Message: One or more fields contain
| incorrect values: Request Id: 2dd68334-2530-4284-b326-48e03b5789b7 Error
| Details: [Code= ValidationError, Message= 'url' should not be empty.,
| Target= url] [Code= ValidationError, Message= 'protocol' should not be
| empty., Target= protocol]
```

### Issue script & Debug output

```PowerShell
Script:

$ApiMgmtContext = New-AzApiManagementContext -ResourceGroupName $ApimResourceGroup -ServiceName $ApiMgmtName
$BackendCredential = New-AzApiManagementBackendCredential -Header @{"x-functions-key" = @("{{valval}}") }
New-AzApiManagementBackend `
-Context $ApiMgmtContext `
-BackendId $BackendName `
-Protocol http `
-Url "https://my-domain.com/api" `
-Credential $BackendCredential

Logs:

DEBUG: Initializing ConditionalAssemblyContext. PSEdition is [Core]. PSVersion is [7.4.6].
DEBUG: Initializing ConditionalAssemblyProvider. AssemblyRootPath is [/home/tpawel/.local/share/powershell/Modules/Az.Accounts/4.0.0/StartupScripts/../lib].
DEBUG: Registering Az shared AssemblyLoadContext.
DEBUG: AssemblyLoadContext registered.
DEBUG: Initializing PSStyle.
DEBUG: Got version 0 of Az
DEBUG: Got version 0 of Az.Accounts
DEBUG: 5:07:11 PM - [ConfigManager] Got nothing from [DisplaySecretsWarning], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: 5:07:11 PM - NewAzureApiManagementContext begin processing with ParameterSet 'ContextParameterSet'.
DEBUG: 5:07:11 PM - using account id '[REDACTED]'...
DEBUG: 5:07:11 PM - [ConfigManager] Got nothing from [DisplayBreakingChangeWarning], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: 5:07:11 PM - [ConfigManager] Got nothing from [DisplaySecretsWarning], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: 5:07:11 PM - [ConfigManager] Got nothing from [DisplayRegionIdentified], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: 5:07:11 PM - [ConfigManager] Got nothing from [CheckForUpgrade], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: AzureQoSEvent: Module: Az.ApiManagement:4.0.5; CommandName: New-AzApiManagementContext; PSVersion: 7.4.6; IsSuccess: True; Duration: 00:00:00.0195837; SanitizeDuration: 00:00:00.0006008
DEBUG: 5:07:11 PM - [ConfigManager] Got nothing from [EnableDataCollection], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: 5:07:11 PM - NewAzureApiManagementContext end processing.
Importing api...
Creating backend
DEBUG: 5:07:11 PM - [ConfigManager] Got nothing from [DisplaySecretsWarning], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: 5:07:11 PM - NewAzureApiManagementBackendCredential begin processing with ParameterSet '__AllParameterSets'.
DEBUG: 5:07:11 PM - using account id '[REDACTED]'...
DEBUG: 5:07:11 PM - [ConfigManager] Got nothing from [DisplayBreakingChangeWarning], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: 5:07:11 PM - [ConfigManager] Got nothing from [DisplaySecretsWarning], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: 5:07:11 PM - [ConfigManager] Got nothing from [DisplayRegionIdentified], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: 5:07:11 PM - [ConfigManager] Got nothing from [CheckForUpgrade], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: AzureQoSEvent: Module: Az.ApiManagement:4.0.5; CommandName: New-AzApiManagementBackendCredential; PSVersion: 7.4.6; IsSuccess: True; Duration: 00:00:00.0011815; SanitizeDuration: 00:00:00.0002764
DEBUG: 5:07:11 PM - [ConfigManager] Got nothing from [EnableDataCollection], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: 5:07:11 PM - NewAzureApiManagementBackendCredential end processing.
DEBUG: 5:07:11 PM - [ConfigManager] Got nothing from [DisplaySecretsWarning], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: 5:07:11 PM - NewAzureApiManagementBackend begin processing with ParameterSet '__AllParameterSets'.
DEBUG: 5:07:11 PM - using account id '[REDACTED]'...
DEBUG: 5:07:11 PM - [ConfigManager] Got nothing from [DisplayBreakingChangeWarning], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: [Common.Authentication]: Authenticating using Account: '[REDACTED]', environment: 'AzureCloud', tenant: '[REDACTED]'
DEBUG: 5:07:11 PM - [ConfigManager] Got nothing from [DisableInstanceDiscovery], Module = [], Cmdlet = []. Returning default value [False].
DEBUG: 5:07:11 PM - [ConfigManager] Got [False] from [EnableLoginByWam], Module = [], Cmdlet = [].
DEBUG: 5:07:11 PM - [SilentAuthenticator] Calling SharedTokenCacheCredential.GetTokenAsync - TenantId:'[REDACTED]', Scopes:'https://management.core.windows.net//.default', AuthorityHost:'https://login.microsoftonline.com/', UserId:'[REDACTED]'
DEBUG: SharedTokenCacheCredential.GetToken invoked. Scopes: [ https://management.core.windows.net//.default ] ParentRequestId:
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 11f635c7-a96d-423c-95db-8cbcdf3db2e5] IsLegacyAdalCacheEnabled: yes
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 11f635c7-a96d-423c-95db-8cbcdf3db2e5] [Region discovery] Not using a regional authority.
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 11f635c7-a96d-423c-95db-8cbcdf3db2e5] [Region discovery] Not using a regional authority.
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 11f635c7-a96d-423c-95db-8cbcdf3db2e5] IsLegacyAdalCacheEnabled: yes
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 11f635c7-a96d-423c-95db-8cbcdf3db2e5] IsLegacyAdalCacheEnabled: yes
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z] Found 1 cache accounts and 0 broker accounts
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z] Returning 1 accounts
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 1005b4fe-f3c3-4f6d-ba13-af98c17946cb] MSAL MSAL.CoreCLR with assembly version '4.65.0.0'. CorrelationId(1005b4fe-f3c3-4f6d-ba13-af98c17946cb)
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 1005b4fe-f3c3-4f6d-ba13-af98c17946cb] === AcquireTokenSilent Parameters ===
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 1005b4fe-f3c3-4f6d-ba13-af98c17946cb] LoginHint provided: False
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 1005b4fe-f3c3-4f6d-ba13-af98c17946cb] Account provided: True
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 1005b4fe-f3c3-4f6d-ba13-af98c17946cb] ForceRefresh: False
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 1005b4fe-f3c3-4f6d-ba13-af98c17946cb]
=== Request Data ===
Authority Provided? - True
Scopes - https://management.core.windows.net//.default
Extra Query Params Keys (space separated) -
ApiId - AcquireTokenSilent
IsConfidentialClient - False
SendX5C - False
LoginHint ? False
IsBrokerConfigured - False
HomeAccountId - False
CorrelationId - 1005b4fe-f3c3-4f6d-ba13-af98c17946cb
UserAssertion set: False
LongRunningOboCacheKey set: False
Region configured:

DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 1005b4fe-f3c3-4f6d-ba13-af98c17946cb] === Token Acquisition (SilentRequest) started:
Scopes: https://management.core.windows.net//.default
Authority Host: login.microsoftonline.com
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 1005b4fe-f3c3-4f6d-ba13-af98c17946cb] [Region discovery] Not using a regional authority.
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 1005b4fe-f3c3-4f6d-ba13-af98c17946cb] Access token is not expired. Returning the found cache entry. [Current time (12/04/2024 17:07:12) - Expiration Time (12/04/2024 18:25:45 +00:00) - Extended Expiration Time (12/04/2024 18:25:45 +00:00)]
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 1005b4fe-f3c3-4f6d-ba13-af98c17946cb] Returning access token found in cache. RefreshOn exists ? False
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 1005b4fe-f3c3-4f6d-ba13-af98c17946cb] [Region discovery] Not using a regional authority.
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 1005b4fe-f3c3-4f6d-ba13-af98c17946cb]
=== Token Acquisition finished successfully:
DEBUG: False MSAL 4.65.0.0 MSAL.CoreCLR .NET 8.0.10 Linux [2024-12-04 17:07:12Z - 1005b4fe-f3c3-4f6d-ba13-af98c17946cb] AT expiration time: 12/4/2024 6:25:45 PM +00:00, scopes: https://management.core.windows.net//.default https://management.core.windows.net//user_impersonation. source: Cache
DEBUG: SharedTokenCacheCredential.GetToken succeeded. Scopes: [ https://management.core.windows.net//.default ] ParentRequestId: ExpiresOn: 2024-12-04T18:25:45.0000000+00:00
DEBUG: [Common.Authentication]: Received token with LoginType 'User', Tenant: [REDACTED], UserId: '[REDACTED]'
DEBUG: ============================ HTTP REQUEST ============================

HTTP Method:
PUT

Absolute Uri: [REDACTED]

Headers:
Accept-Language : en-US
x-ms-client-request-id : 9a2e8cfe-e4da-445f-a081-2a9d8c5bc4a2

Body:
{
"properties": {
"credentials": {
"header": {
"x-functions-key": [
"{{valval}}"
]
}
}
}
}

DEBUG: ============================ HTTP RESPONSE ============================

Status Code:
BadRequest

Headers:
Cache-Control : no-cache
Pragma : no-cache
Strict-Transport-Security : max-age=31536000; includeSubDomains
X-Content-Type-Options : nosniff
x-ms-request-id : ee31d0aa-d430-4fdc-a4ea-9955a1a71be7
x-ms-ratelimit-remaining-subscription-writes: 199
x-ms-ratelimit-remaining-subscription-global-writes: 2999
x-ms-correlation-request-id : ee31d0aa-d430-4fdc-a4ea-9955a1a71be7
x-ms-routing-request-id : NORTHEUROPE:20241204T170712Z:ee31d0aa-d430-4fdc-a4ea-9955a1a71be7
X-Cache : CONFIG_NOCACHE
X-MSEdge-Ref : Ref A: 6255015791FA43A7B8DF15942AB31301 Ref B: AMS231032609033 Ref C: 2024-12-04T17:07:12Z
Date : Wed, 04 Dec 2024 17:07:11 GMT

Body:
{
"error": {
"code": "ValidationError",
"message": "One or more fields contain incorrect values:",
"details": [
{
"code": "ValidationError",
"target": "url",
"message": "'url' should not be empty."
},
{
"code": "ValidationError",
"target": "protocol",
"message": "'protocol' should not be empty."
}
]
}
}

DEBUG: 5:07:12 PM - [ConfigManager] Got nothing from [EnableErrorRecordsPersistence], Module = [], Cmdlet = []. Returning default value [False].
New-AzApiManagementBackend: deploy.ps1:104:5
Line |
104 | New-AzApiManagementBackend `
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| Error Code: ValidationError Error Message: One or more
| fields contain incorrect values: Request Id:
| ee31d0aa-d430-4fdc-a4ea-9955a1a71be7 Error Details: [Code=
| ValidationError, Message= 'url' should not be empty.,
| Target= url] [Code= ValidationError, Message= 'protocol'
| should not be empty., Target= protocol]
DEBUG: 5:07:12 PM - [ConfigManager] Got nothing from [DisplayBreakingChangeWarning], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: 5:07:12 PM - [ConfigManager] Got nothing from [DisplayRegionIdentified], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: 5:07:12 PM - [ConfigManager] Got nothing from [CheckForUpgrade], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: AzureQoSEvent: Module: Az.ApiManagement:4.0.5; CommandName: New-AzApiManagementBackend; PSVersion: 7.4.6; IsSuccess: False; Duration: 00:00:01.2171898; SanitizeDuration: 00:00:00; Exception:
Error Code: ValidationError
Error Message: One or more fields contain incorrect values:
Request Id: ee31d0aa-d430-4fdc-a4ea-9955a1a71be7
Error Details:
[Code= ValidationError, Message= 'url' should not be empty., Target= url]
[Code= ValidationError, Message= 'protocol' should not be empty., Target= protocol]
;
DEBUG: 5:07:12 PM - [ConfigManager] Got nothing from [EnableDataCollection], Module = [], Cmdlet = []. Returning default value [True].
DEBUG: 5:07:12 PM - NewAzureApiManagementBackend end processing.
```

### Environment data

```PowerShell
Name Value
---- -----
PSVersion 7.4.6
PSEdition Core
GitCommitId 7.4.6
OS Ubuntu 24.04.1 LTS
Platform Unix
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1
WSManStackVersion 3.0
```

### Module versions

```PowerShell
Version Name Repository
------- ---- ----------
4.1.1 Az.Functions PSGallery
4.0.5 Az.ApiManagement PSGallery
4.0.0 Az.Accounts PSGallery
```

### Error output

```PowerShell

```

Start from the New-AzApiManagementBackend command and its parameter handling, then compare the supplied -Protocol and -Url values with the HTTP request body shown in the issue. Reproduce the failure with the provided PowerShell script; done means the request preserves both values and the backend is created successfully without validation errors.

Written by the indexing model from the issue text.