Generate guid for FormatViewDefinition InstanceId if not provided (#11896)

src/System.Management.Automation/FormatAndOutput/common/DisplayDatabase/displayDescriptionData.cs

@@ -697,6 +697,7 @@ namespace System.Management.Automation
 
             Name = name;
             Control = control;
+            InstanceId = Guid.NewGuid();
         }
     }
 

test/powershell/Modules/Microsoft.PowerShell.Utility/Export-FormatData.Tests.ps1

@@ -153,4 +153,22 @@ Describe "Export-FormatData" -Tags "CI" {
             $runspace.Close()
         }
     }
+
+    It 'Should be able to export multiple views' {
+        $listControl = [System.Management.Automation.ListControl]::Create().StartEntry().AddItemProperty('test').AddItemProperty('test2').EndEntry().EndList()
+        $tableControl = [System.Management.Automation.TableControl]::Create().StartRowDefinition().AddPropertyColumn('test').AddPropertyColumn('test2').EndRowDefinition().EndTable()
+
+        $listView = [System.Management.Automation.FormatViewDefinition]::new('Default', $listControl)
+        $tableView = [System.Management.Automation.FormatViewDefinition]::new('Default', $tableControl)
+
+        $list = New-Object System.Collections.Generic.List[System.Management.Automation.FormatViewDefinition]
+        $list.Add($listView)
+        $list.Add($tableView)
+
+        $typeDef = [System.Management.Automation.ExtendedTypeDefinition]::new('TestTypeName', $list)
+        $filePath = Join-Path $TestDrive "test.format.ps1xml"
+        $typeDef | Export-FormatData -Path $filePath
+        [xml]$xml = Get-Content -Path $filePath
+        @($xml.Configuration.ViewDefinitions.View).Count | Should -Be 2
+    }
 }