Yang parser not able to deal with short-case-stmt in augment/uses-augment

Issue: module stated below causes NullPointerException in code generator.

Solution: short-case-stmt should be expanded during parsing to full case-stmt to avoid it.

module uses-augment-test {

yang-version 1;
prefix "uat";
namespace "urn:uat";

grouping grp1 {
uses grp2 {
augment mychoice {
//here it comes...
leaf myleaf1

{ type string; }

}
}
}

grouping grp2 {
choice mychoice {
leaf myleaf2

{ type string; }

}
}

container cont {
uses grp1;
leaf myleaf3

{ type string; }

}

}