code: @Override
  	protected LightweightTypeReference getCommonSuperType(List<LightweightTypeReference> types, ITypeComputationState state) {
  		if (types.isEmpty()) {
  			return null;
  		}
  		LightweightTypeReference result = super.getCommonSuperType(types, state);
  		return result;
  	}
docs: Specializes the super implementation such that is allows an empty list of types.
  Returns {@code null} for those.
  
  {@inheritDoc}