private Object convertResult(Object value) {
            if (value instanceof RawData raw) {
                return new RawBase64(raw.getData());
            }
            return value;
        }
Constructs the grouping result tree that corresponds to the parameters given to this builder. This method might
fail due to unsupported constructs in the results, in which case an exception is thrown.

@throws IllegalInputException Thrown if the grouping result contains unsupported constructs.
container-search/src/main/java/com/yahoo/search/grouping/vespa/ResultBuilder.java