private void addItemValueType(ShortList itemValueType) {
            if (fUseItemValueTypeVector) {
                fItemValueTypes.add(itemValueType);
            }
            else if (fItemValueTypesLength++ == 0) {
                fItemValueType = itemValueType;
            }
            else if (!(fItemValueType == itemValueType ||
                    (fItemValueType != null && fItemValueType.equals(itemValueType)))) {
                fUseItemValueTypeVector = true;
                if (fItemValueTypes == null) {
                    fItemValueTypes = new Vector(fItemValueTypesLength * 2);
                }
                for (int i = 1; i < fItemValueTypesLength; ++i) {
                    fItemValueTypes.add(fItemValueType);
                }
                fItemValueTypes.add(itemValueType);
            }
        }