/**
* Gets feed attribute.
*
* @param index index
* @param field field
* @return attribute or <code>null</code> if not available
*/
protected IFeedAttribute getFeedAttribute(Map<String, IFeedAttribute> index, DcatField field) {
for (List<String> additives : field.getIndex()) {
List<IFeedAttribute> lstAttributes = new ArrayList<IFeedAttribute>();
for (String indexName : additives) {
IFeedAttribute attr = index.get(indexName);
if (attr != null && !attr.isEmpty()) {
lstAttributes.add(attr);
}
}
if (lstAttributes.size() == 1) return lstAttributes.get(0);
if (lstAttributes.size() > 1)
return IFeedAttribute.Factory.createSum(lstAttributes, field.getJoinOperator());
}
return null;
}