Missing required property 'Hit.index'

I've recently upgraded an on-premise Elastic 7.17.19 server to 8.13.0. Since I had problems with the java client I had (especially with digesting) I've decided to also upgrade by java client to 8.13 with jackson 2.17.0. I've rewritten all elastic code and queries. I'm facing runtime problems with HitMetadata. I don't know what I'm doing wrong but it seems that its in the client api it self.

Here is my method:

public <T extends IElasticDocument> ResponseWrapper<T> findElasticDocuments(SearchRequest.Builder query, Highlight.Builder highlight, boolean fullScroll, 
			Map<String, Aggregation> aggs, int size, Class<T> regulationClass, SortOptions ... sort) {
		String pitId = null;
		try {
			String indexName = ReflectionUtils.getAnnotation(regulationClass, IndexName.class).value();
			String[] fullIndex = getStaticValue(regulationClass, "fullIndex");

			final Time keepAlive = new Time.Builder().time("3m").build();
			final OpenPointInTimeResponse pitResp = client.openPointInTime(req -> req.index(indexName).keepAlive(keepAlive));
			final String initialPitId = pitResp.id();
			pitId = initialPitId;
			query.size(size)
				.pit(pit -> pit.id(initialPitId).keepAlive(keepAlive)) // This is the initial pit. It would be better to use the pit from the last result
				.source(SourceConfig.of(sc -> 
					sc.filter(SourceFilter.of(sf -> 
						sf.includes("", fullIndex))
					)
				));
			
			if (null != highlight)
				query.highlight(h -> highlight);
			if (null != sort && 0 < sort.length)
				query.sort(Arrays.asList(sort));
			if (null != aggs && !aggs.isEmpty())
				query.aggregations(aggs);

			String lastId = null; // holds the last retrieved result id.
			ResponseWrapper<T> wrapper = new ResponseWrapper<>();
			List<T> results = new ArrayList<>();
			long took = 0;
			do {
				if (null != lastId) {
					query = query.searchAfter(FieldValue.of(lastId));
				}
				SearchRequest req = query.build();
				SearchResponse<T> response = client.search(req, regulationClass);
				took += response.took();
				List<Hit<T>> hits = response.hits().hits();
				if (null != hits && !hits.isEmpty() && 1000 >= results.size()) {
					if (fullScroll) {
						if (1000 >= results.size()) {
							lastId = convertResults(results, hits);
						}
					}
					else {
						wrapper.setScrollId(lastId);
						lastId = null;
					}
				}
				else {
					wrapper.setScrollId(lastId);
					lastId = null;
				}
			} while (lastId != null);
			
			
			wrapper.setTook(took);
			wrapper.setResults(results);
			return wrapper;
		}
		catch (Exception e) {
			logger.error(DEFAULT_ERROR_MSG, e);
			return new ResponseWrapper<>(new ArrayList<>());
		}
		finally {
			ClosePointInTimeResponse pitCloseResp;
			try {
				final String closePitId = pitId;
				pitCloseResp = client.closePointInTime(req -> req.id(closePitId));
				if (!pitCloseResp.succeeded())
					logger.warn("Search request with id: {} failed to close", closePitId);
			}
			catch (ElasticsearchException | IOException e) {
				logger.warn("Search request with id: {} failed to close", pitId);
			}
			
		}
	}

This method accepts a query build somewhere else and handles some generic stuff that is good for all the indexes I search. With debug I can see the json request coming out is as follows:

{
    "_source": {
        "includes": [
            "",
            "neoId",
            "version",
            "createDate",
            "updateDate",
            "superIndex",
            "index",
            "fileNumber",
            "title",
            "status",
            "regulationType",
            "subject",
            "directiveType",
            "directiveNumber",
            "publishDate",
            "deleted",
            "appliesTo",
            "relatedToCodex",
            "relatedCodexIndexNumber",
            "effectiveDate",
            "dateResolution",
            "hasObligation",
            "cancellationDate",
            "newDirectiveIndex",
            "newDirectiveNumber",
            "oldDirectiveIndex",
            "oldDirectiveNumber",
            "searchable",
            "submissionCommentsDate",
            "regulationCount",
            "textEditor",
            "hasNewerRelease"
        ]
    },
    "highlight": {
        "type": "fvh",
        "fields": {
            "content.content": {
                "fragment_size": 200,
                "number_of_fragments": 1
            }
        }
    },
    "query": {
        "bool": {
            "must": [
                {
                    "term": {
                        "searchable": {
                            "value": true
                        }
                    }
                },
                {
                    "dis_max": {
                        "boost": 1.2000000476837158,
                        "queries": [
                            {
                                "match_phrase": {
                                    "title": {
                                        "boost": 6.0,
                                        "analyzer": "hebrew",
                                        "query": "דירקטור"
                                    }
                                }
                            },
                            {
                                "match": {
                                    "title": {
                                        "boost": 1.5,
                                        "analyzer": "hebrew",
                                        "operator": "and",
                                        "query": "דירקטור"
                                    }
                                }
                            },
                            {
                                "match_phrase": {
                                    "content.content": {
                                        "boost": 4.0,
                                        "analyzer": "hebrew",
                                        "query": "דירקטור"
                                    }
                                }
                            }
                        ],
                        "tie_breaker": 0.7
                    }
                }
            ],
            "must_not": [
                {
                    "term": {
                        "directiveType": {
                            "value": "87"
                        }
                    }
                }
            ]
        }
    },
    "size": 1000,
    "sort": [
        {
            "_score": {
                "order": "desc"
            }
        },
        {
            "publishDate": {
                "order": "desc"
            }
        },
        {
            "index": {
                "order": "desc"
            }
        },
        {
            "fileNumber": {
                "order": "asc"
            }
        }
    ]
}

Running this request in postman yields good results. Here is one

{
    "took": 2637,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 365,
            "relation": "eq"
        },
        "max_score": null,
        "hits": [
            {
                "_index": "regulation_release",
                "_id": "YsOM1nwB0netDWQ5M7XV",
                "_score": 115.92962,
                "_source": {
                    "updateDate": "2021-10-31T15:40:03",
                    "fileNumber": 1,
                    "subject": [
                        "8"
                    ],
                    "publishDate": "2021-10-31",
                    "superIndex": 1544,
                    "appliesTo": [
                        "2"
                    ],
                    "title": "some good title data",
                    "dateResolution": false,
                    "oldDirectiveIndex": null,
                    "hasObligation": "NONE",
                    "cancellationDate": null,
                    "createDate": "2021-10-31T15:31:15",
                    "relatedCodexIndexNumber": null,
                    "newDirectiveNumber": null,
                    "relatedToCodex": false,
                    "index": 182118,
                    "oldDirectiveNumber": null,
                    "version": 3,
                    "neoId": 16641,
                    "searchable": true,
                    "regulationType": "settlement",
                    "deleted": false,
                    "directiveType": "10",
                    "newDirectiveIndex": null,
                    "submissionCommentsDate": null,
                    "directiveNumber": null,
                    "regulationCount": 1,
                    "effectiveDate": null,
                    "status": "DRAFT"
                },
                "highlight": {
                    "content.content": ["some good content highlight data"]
                },
                "sort": [
                    115.92962,
                    1635638400000,
                    182118,
                    1
                ]
            }
///

When parsing this response I get an error "Missing required property 'Hit.index' ".

I've tried to follow with debug. What I see is that I get a hit with all necessary details for the source and then I get another Hit for the highlight and sort which except for these to fields does not have the other fields. Now as I understand it the highlight and sort fields should not have been separated from the first hit and should not be on their own.

If I comment out the highlight, sort and aggregations addition to the request builder then the request fails completely on problems with parsing HitMetadata: Unexpected JSON event 'END_OBJECT' instead of '[START_OBJECT, KEY_NAME]'

I have no idea how to resolve this and what I might be doing wrong. Any help would be great.

Thanks