Java 8 compiler failure

TestCase.java

import java.util.Collection;
import java.util.stream.Collectors;

public class TestCase
{
    Class clazz;
    Collection<Target> targets;

    public Collection<Target> getTargets()
    {
        Collection<Target> myTargets = targets.stream()
                .filter( t -> t.isApplicable( clazz ) )
                .collect( Collectors.toList());
        return myTargets;
    }

    public interface Target
    {
        boolean isApplicable(Class<? extends MainType> clazz);
    }

    public interface MainType
    {
    }
}