2.14pre1 null values as default parameter of macro

Hello!

We're are running an application with an ancient prerelease of freemarker 2.4 (namely freemarker2.4.0_090807svn.jar). So far it really works well.

Today I tried to upgrade the application to freemarker-2.4pre1.jar and now the following construct doesn't work anymore:

[#macro mainLayout layout=null]
	<!--html here -->
	[#if layout??]	 
		${layout}
	[/#if]
	<!--html also here-->
[/#macro]

Exception is:

freemarker.core.InvalidReferenceException: Expression null is undefined on line 71, column 27 in ilbi/admin/admin.ftl.
	at freemarker.core.helpers.DefaultReferenceChecker.assertNonNull(DefaultReferenceChecker.java:18)

Is this the desired behaviour for 2.4? If so I'll update my parameter specifications.

thanks,
Florian

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