Code completion for enum constant does not add necessary import or qualifier

Similar to #367 and #435, completion in the following situation does not add import or qualifier.
```java
import java.util.concurrent.TimeUnit
public class Other {
  public static void method(TimeUnit unit) { }
}
```
Groovy script:
```groovy
Other.method(SE|) // choose "SECONDS : TimeUnit" completion proposal; no import or qualifier is inserted
```
