Don't NullRef when performing Get-AzureDeployment when the cloud service has extended configuration

Author: spaoliello

src/ServiceManagement/Compute/Commands.ServiceManagement/Model/CertificateConfiguration.cs

@@ -19,5 +19,7 @@ public class CertificateConfiguration
         public string Thumbprint { get; set; }
 
         public string ThumbprintAlgorithm { get; set; }
+
+        public string SourceLocation { get; set; }
     }
 }

src/ServiceManagement/Compute/Commands.ServiceManagement/Model/RoleConfiguration.cs

@@ -45,8 +45,9 @@ public RoleConfiguration(XElement data)
                 {
                     var certificate = new CertificateConfiguration
                     {
-                        Thumbprint = setting.Attribute("thumbprint").Value,
-                        ThumbprintAlgorithm = setting.Attribute("thumbprintAlgorithm").Value
+                        Thumbprint = setting.Attribute("thumbprint") == null ? null : setting.Attribute("thumbprint").Value,
+                        ThumbprintAlgorithm = setting.Attribute("thumbprintAlgorithm") == null ? null : setting.Attribute("thumbprintAlgorithm").Value,
+                        SourceLocation = setting.Attribute("sourceLocation") == null ? null : setting.Attribute("sourceLocation").Value,
                     };
 
                     this.Certificates.Add(setting.Attribute("name").Value, certificate);
@@ -104,8 +105,18 @@ internal XElement Serialize()
             {
                 XElement certificateElement = new XElement(this.ns + "Certificate");
                 certificateElement.SetAttributeValue("name", certificate.Key);
-                certificateElement.SetAttributeValue("thumbprint", certificate.Value.Thumbprint);
-                certificateElement.SetAttributeValue("thumbprintAlgorithm", certificate.Value.ThumbprintAlgorithm);
+                if (certificate.Value.Thumbprint != null)
+                {
+                    certificateElement.SetAttributeValue("thumbprint", certificate.Value.Thumbprint);
+                }
+                if (certificate.Value.ThumbprintAlgorithm != null)
+                {
+                    certificateElement.SetAttributeValue("thumbprintAlgorithm", certificate.Value.ThumbprintAlgorithm);
+                }
+                if (certificate.Value.SourceLocation != null)
+                {
+                    certificateElement.SetAttributeValue("sourceLocation", certificate.Value.SourceLocation);
+                }
                 certificatesElement.Add(certificateElement);
             }