Returning nested data in fields API

modules/mapper-extras/src/main/java/org/elasticsearch/index/mapper/TokenCountFieldMapper.java

@@ -83,7 +83,7 @@ static class TokenCountFieldType extends NumberFieldMapper.NumberFieldType {
         @Override
         public ValueFetcher valueFetcher(SearchExecutionContext context, String format) {
             if (hasDocValues() == false) {
-                return lookup -> List.of();
+                return (lookup, ignoredFields) -> List.of();
             }
             return new DocValueFetcher(docValueFormat(format, null), context.getForField(this));
         }