Make Get-AzPolicyDefinitions fail if -Id is nonexistent (#21041)

* Make Get-AzPolicyDefinitions fail if -Id is nonexistent

* Move changelog comments to correct file

* Remove extra files pushed by mistake

* Update src/Resources/Resources/ChangeLog.md

---------

Co-authored-by: Beisi Zhou <[email protected]>

Author: mentat9

src/Resources/ResourceManager/Implementation/Policy/GetAzurePolicyDefinition.cs

@@ -127,7 +127,7 @@ private async Task<ResponseWithContinuation<JObject[]>> GetResources(ListFilter
                 }
                 catch (ErrorResponseMessageException ex)
                 {
-                    if (!ex.Message.StartsWith("PolicyDefinitionNotFound", StringComparison.OrdinalIgnoreCase))
+                    if (!ex.Message.StartsWith("PolicyDefinitionNotFound", StringComparison.OrdinalIgnoreCase) || string.IsNullOrEmpty(this.Name))
                     {
                         throw;
                     }

src/Resources/Resources.Test/ScenarioTests/PolicyTests.ps1

@@ -2045,7 +2045,6 @@ function Test-GetPolicyDefinitionParameters
     Assert-ThrowsContains { Get-AzPolicyDefinition -Name $someName -Id $someId -Custom } $parameterSetError
 
     # validate remaining parameter combinations starting with -Id
-    $ok = Get-AzureRmPolicyDefinition -Id $goodId
     Assert-ThrowsContains { Get-AzPolicyDefinition -Id $goodId -ManagementGroupName $someManagementGroup } $parameterSetError
     Assert-ThrowsContains { Get-AzPolicyDefinition -Id $goodId -SubscriptionId $subscriptionId } $parameterSetError
     Assert-ThrowsContains { Get-AzPolicyDefinition -Id $goodId -BuiltIn } $parameterSetError

src/Resources/Resources/ChangeLog.md

@@ -19,6 +19,7 @@
 -->
 
 ## Upcoming Release
+* Updated behavior of Get-AzPolicyDefinition which previously returned all definitions when -Id was provided with a nonexistent policy definition id. Fixed to correctly throw a 404 exception in this case.
 
 ## Version 6.5.2
 * Fixed query issue when objectId in assignment is empty for `Get-DenyAssignment`