no constructor for indentityref in union

The generated java code for union with identityref doens't include a constructor for identityref.

module union-with-identityref {
yang-version 1;
namespace "urn:opendaylight:yang:union:test";
prefix "uniontest";

description "test union with identityref";

revision "2016-05-09";

identity ident-base;
identity ident-one

{ base ident-base; }
identity ident-two { base ident-base; }

typedef union-type {
type union {
type uint8;
type identityref

{ base ident-base; }

}
}
}

generated java code
public class UnionType
implements Serializable {
private static final long serialVersionUID = 4724108168179933454L;
private final java.lang.Short _uint8;
private final char[] _value;

public UnionType(java.lang.Short _uint8)

{ super(); this._uint8 = _uint8; this._value = _uint8.toString().toCharArray(); }

...