ModelDeclaration sourceModel = source.findDeclaration();
assert sourceModel != null;
List<MappingFactor> results = Lists.create();
for (AstPropertyFolding propertyFolding : folding.properties) {
PropertyDeclaration targetProperty = model.findPropertyDeclaration(propertyFolding.target.identifier);
PropertyMappingKind mapping = resolveAggregateFunction(propertyFolding.aggregator);
if (targetProperty != null && mapping != null) {
results.add(new MappingFactor(
source.getName(),
mapping,
source.createPropertySymbol(propertyFolding.source),