module union-restrictions {
yang-version 1;
namespace "urn:yang.foo";
prefix "foo";

import ietf-inet-types

{ prefix inet; }

container foo {
leaf address {
type inet:host

{ //blah,blah,blah }

}
}
}

Binding Java API generator fails with "strange" (not relevant from user's point of view) error:

java.lang.IllegalArgumentException: Type cannot have Package Name referenced as NULL!
at com.google.common.base.Preconditions.checkArgument(Preconditions.java:92)
at org.opendaylight.yangtools.sal.java.api.generator.GeneratorUtil.putTypeIntoImports(GeneratorUtil.java:138)
at org.opendaylight.yangtools.sal.java.api.generator.BaseTemplate.importedName(BaseTemplate.java:244)
at org.opendaylight.yangtools.sal.java.api.generator.InterfaceTemplate.generateMethods(InterfaceTemplate.java:369)
at org.opendaylight.yangtools.sal.java.api.generator.InterfaceTemplate.body(InterfaceTemplate.java:113)
at org.opendaylight.yangtools.sal.java.api.generator.BaseTemplate.generate(BaseTemplate.java:77)