/// <summary>
		///     Normalizes the <paramref name="methodDeclaration" /> and adds the generated members.
		/// </summary>
		/// <param name="methodDeclaration">The method declaration that should be normalized.</param>
		private MethodDeclarationSyntax NormalizeExternMethod(MethodDeclarationSyntax methodDeclaration)
		{
			var originalDeclaration = methodDeclaration;
			var methodDelegate = CreateDelegate(methodDeclaration);
			var methodField = CreateField(methodDelegate);

			// Add the [Required] attribute if it is not already present
			if (!methodDeclaration.HasAttribute<RequiredAttribute>(SemanticModel))
			{
				methodDeclaration = methodDeclaration.RemoveTrivia();
				methodDeclaration = methodDeclaration.WithAttributeLists(methodDeclaration.AttributeLists.Add(_requiredAttribute.WithTrailingSpace()));
			}

			// Remove the 'extern' keyword from the method
			var externIndex = methodDeclaration.Modifiers.IndexOf(SyntaxKind.ExternKeyword);
			methodDeclaration = methodDeclaration.WithModifiers(methodDeclaration.Modifiers.RemoveAt(externIndex));

			// Add the [DebuggerHidden] attribute if it is not already present
			if (!originalDeclaration.HasAttribute<DebuggerHiddenAttribute>(SemanticModel))
				methodDeclaration = methodDeclaration.WithAttributeLists(methodDeclaration.AttributeLists.Add(_debuggerHiddenAttribute));

			// Replace the method's body and ensure that we don't modify the line count of the containing type
			methodDeclaration = AddBackingFieldAttribute(methodDeclaration);
			methodDeclaration = ReplaceBodyWithDelegateInvocation(methodDeclaration);
			methodDeclaration = methodDeclaration.NormalizeWhitespace();
			methodDeclaration = methodDeclaration.WithTrivia(originalDeclaration);

			++_portCount;
			AddMembers(originalDeclaration.GetMethodSymbol(SemanticModel).ContainingType, methodField, methodDelegate);
			return methodDeclaration.EnsureLineCount(originalDeclaration);
		}