NuGet.Manifest.CheckSchemaVersion C# (CSharp) Method

        private static void CheckSchemaVersion(XDocument document)
        {
            // Get the metadata node and look for the schemaVersion attribute
            XElement metadata = GetMetadataElement(document);

            if (metadata != null)
            {
                // Yank this attribute since we don't want to have to put it in our xsd
                XAttribute schemaVersionAttribute = metadata.Attribute(SchemaVersionAttributeName);

                if (schemaVersionAttribute != null)
                {
                    schemaVersionAttribute.Remove();
                }

                // Get the package id from the metadata node
                string packageId = GetPackageId(metadata);

                // If the schema of the document doesn't match any of our known schemas
                if (!ManifestSchemaUtility.IsKnownSchema(document.Root.Name.Namespace.NamespaceName))
                {
                    throw new InvalidOperationException(
                            String.Format(CultureInfo.CurrentCulture,
                                          NuGetResources.IncompatibleSchema,
                                          packageId,
                                          typeof(Manifest).Assembly.GetName().Version));
                }
            }
        }