EDIT

                node.setParent(currentnode);

                children.add(node);

            }

        }

        else if(value instanceof Sequence){

            Set<SingleRead> singleReads = ((Sequence) value).getSingleReads();

            }

            return children.toArray();

        }

	        List<DerivedUnit> derivates = getDerivates((SpecimenOrObservationBase<?>) value);

	        for (DerivedUnit derivedUnit:derivates) {

                TreeNode node = new TreeNode(derivedUnit);

        else if(element instanceof Sequence){

            return !((Sequence)element).getSingleReads().isEmpty();

        }

	        SpecimenOrObservationBase<?> specimenOrObservation = (SpecimenOrObservationBase<?>)element;

	        for(DerivationEvent event:specimenOrObservation.getDerivationEvents()){

	            if(!event.getDerivatives().isEmpty()){