import java.util.Map;

public class NullsAndGenerics<E> {

  private boolean enableProtoAnnotations;

  @SuppressWarnings("unchecked")
  private <T, O extends Message, E extends ProtoElement> T getProtoExtension(
      E element, GeneratedExtension<O, T> extension) {
    // Use this method as the chokepoint for all field annotations processing, so we can
    // toggle on/off annotations processing in one place.
    if (!enableProtoAnnotations) {
      return null;
    }
    return (T) element.getOptionFields().get(extension.getDescriptor());
  }

  // stubs of relevant classes
  private class Message {}

  private class ProtoElement {
    public Map<FieldDescriptor, Object> getOptionFields() {
      return null;
    }
  }

  private class FieldDescriptor {}

  private class GeneratedExtension<O, T> {
    public FieldDescriptor getDescriptor() {
      return null;
    }
  }
}