Optional data type and data binding with undef as default value

ORIGINAL REPORT

All the files are in .zip attached file. I have a (very basic) module with the function data.pp as data provider and the default value of a parameter is undef:

function test::data {

  {

    test::foo::param => undef,

  }

}

In the class ::test::foo, I have this code:

class test::foo ( Optional[ String[1] ] $param ) { }

As you can see, the type of the parameter $param is an Optional which means that a undef value is accepted. However, if I test this code:

include '::test::foo'

I have an error:

~# puppet apply /puppet/modules/test/examples/example.pp 

Error: Evaluation Error: Error while evaluating a Function Call, Class[Test::Foo]: expects a value for parameter 'param' at /puppet/modules/test/examples/example.pp:1:1 on node puppet.athome.priv

It seems to me that it's not the expected behavior.
Regards.

PS: currently a possible and simple workaround is to set a undef default value in the declaration of the class like this:

class test::foo ( Optional[ String[1] ] $param = undef ) { }

but you have to set the undef value in two different places.

UPDATE

This is fixed so that if an undef value is bound for a parameter key data binding will assign that undef to the parameter if the parameter does not have a default value expression. Earlier such a binding would have failed and required that the parameter had a default value expression of = undef in order to make a lookup of undef possible.