public Input<?> visitReference(Reference symbol, Context context) {
// only doc level references are allowed here, since other granularities
// should have been resolved by other visitors already
E docLevelExpression = referenceResolver.getImplementation(symbol.info());
if (docLevelExpression == null) {
throw new UnhandledServerException(SymbolFormatter.format("Cannot handle Reference %s", symbol));
}
context.docLevelExpressions.add(docLevelExpression);
return docLevelExpression;
}