Fix issue when importing no-password certificate (Azure#16758)

* fix issue if importing no password certificate

* add change log

Author: BethanyZhou

src/KeyVault/KeyVault/ChangeLog.md

@@ -18,6 +18,7 @@
         - Additional information about change #1
 -->
 ## Upcoming Release
+* Fixed the issue when importing no-password certificate [#16742]
 
 ## Version 4.2.0
 * Added cmdlets: `Invoke-AzKeyVaultKeyRotation`, `Get-AzKeyVaultKeyRotationPolicy` and `Set-AzKeyVaultKeyRotationPolicy`

src/KeyVault/KeyVault/Commands/ImportAzureKeyVaultCertificate.cs

@@ -140,17 +140,7 @@ public override void ExecuteCmdlet()
 
                         if (doImport)
                         {
-                            byte[] base64Bytes;
-
-                            if (Password == null)
-                            {
-                                base64Bytes = userProvidedCertColl.Export(X509ContentType.Pfx);
-                            }
-                            else
-                            {
-                                base64Bytes = userProvidedCertColl.Export(X509ContentType.Pfx, Password.ConvertToString());
-                            }
-
+                            byte[] base64Bytes = userProvidedCertColl.Export(X509ContentType.Pfx, Password?.ConvertToString());
                             string base64CertCollection = Convert.ToBase64String(base64Bytes);
                             certBundle = this.DataServiceClient.ImportCertificate(VaultName, Name, base64CertCollection, Password, Tag == null ? null : Tag.ConvertToDictionary());
                         }
@@ -188,15 +178,8 @@ internal X509Certificate2Collection InitializeCertificateCollection()
             }
 
             X509Certificate2Collection certificateCollection = new X509Certificate2Collection();
-
-            if (null == this.Password)
-            {
-                certificateCollection.Import(certFile.FullName);
-            }
-            else
-            {
-                certificateCollection.Import(certFile.FullName, this.Password.ConvertToString(), X509KeyStorageFlags.Exportable);
-            }
+            
+            certificateCollection.Import(certFile.FullName, this.Password?.ConvertToString(), X509KeyStorageFlags.Exportable);
 
             return certificateCollection;
         }