private static Object getReferencedId(DataRecord next, ReferenceFieldMetadata field) { DataRecord record = (DataRecord) next.get(field); if (record != null) { Collection<FieldMetadata> keyFields = record.getType().getKeyFields(); if (keyFields.size() == 1) { return record.get(keyFields.iterator().next()); } else { List<Object> compositeKeyValues = new ArrayList<Object>(keyFields.size()); for (FieldMetadata keyField : keyFields) { compositeKeyValues.add(record.get(keyField)); } return compositeKeyValues; } } else { return StringUtils.EMPTY; } }