Complete searchMsearchRequest for the new client.

Original Pull Request spring-projects#2231
Closes spring-projects#2156

Author: sothawo

src/main/java/org/springframework/data/elasticsearch/client/elc/RequestConverter.java

@@ -47,6 +47,7 @@
 import co.elastic.clients.elasticsearch.core.bulk.IndexOperation;
 import co.elastic.clients.elasticsearch.core.bulk.UpdateOperation;
 import co.elastic.clients.elasticsearch.core.mget.MultiGetOperation;
+import co.elastic.clients.elasticsearch.core.msearch.MultisearchBody;
 import co.elastic.clients.elasticsearch.core.search.Highlight;
 import co.elastic.clients.elasticsearch.core.search.Rescore;
 import co.elastic.clients.elasticsearch.core.search.SourceConfig;
@@ -1047,26 +1048,120 @@ public <T> SearchRequest searchRequest(Query query, @Nullable Class<T> clazz, In
 	public MsearchRequest searchMsearchRequest(
 			List<ElasticsearchTemplate.MultiSearchQueryParameter> multiSearchQueryParameters) {
 
+		// basically the same stuff as in prepareSearchRequest, but the new Elasticsearch has different builders for a
+		// normal search and msearch
 		return MsearchRequest.of(mrb -> {
 			multiSearchQueryParameters.forEach(param -> {
 				ElasticsearchPersistentEntity<?> persistentEntity = getPersistentEntity(param.clazz);
 
+				var query = param.query;
 				mrb.searches(sb -> sb //
-						.header(h -> h //
-								.index(Arrays.asList(param.index.getIndexNames())) //
-				// todo #2156 add remaining flags for header
-				) //
-						.body(bb -> bb //
-								.query(getQuery(param.query, param.clazz))//
-								.seqNoPrimaryTerm(persistentEntity.hasSeqNoPrimaryTermProperty()).version(true)
-				// todo #2156 add remaining flags for body
+						.header(h -> {
+							h //
+									.index(Arrays.asList(param.index.getIndexNames())) //
+									.routing(query.getRoute()) //
+									.searchType(searchType(query.getSearchType())) //
+									.requestCache(query.getRequestCache()) //
+							;
+
+							if (query.getPreference() != null) {
+								h.preference(query.getPreference());
+							}
+
+							return h;
+						}) //
+						.body(bb -> {
+							bb //
+									.query(getQuery(query, param.clazz))//
+									.seqNoPrimaryTerm(persistentEntity != null ? persistentEntity.hasSeqNoPrimaryTermProperty() : null) //
+									.version(true) //
+									.trackScores(query.getTrackScores()) //
+									.source(getSourceConfig(query)) //
+									.timeout(timeStringMs(query.getTimeout())) //
+							;
+
+							if (query.getPageable().isPaged()) {
+								bb //
+										.from((int) query.getPageable().getOffset()) //
+										.size(query.getPageable().getPageSize());
+							}
+
+							if (!isEmpty(query.getFields())) {
+								bb.fields(fb -> {
+									query.getFields().forEach(fb::field);
+									return fb;
+								});
+							}
+
+							if (!isEmpty(query.getStoredFields())) {
+								bb.storedFields(query.getStoredFields());
+							}
+
+							if (query.isLimiting()) {
+								bb.size(query.getMaxResults());
+							}
+
+							if (query.getMinScore() > 0) {
+								bb.minScore((double) query.getMinScore());
+							}
+
+							if (query.getSort() != null) {
+								List<SortOptions> sortOptions = getSortOptions(query.getSort(), persistentEntity);
+
+								if (!sortOptions.isEmpty()) {
+									bb.sort(sortOptions);
+								}
+							}
+
+							addHighlight(query, bb);
+
+							if (query.getExplain()) {
+								bb.explain(true);
+							}
+
+							if (!isEmpty(query.getSearchAfter())) {
+								bb.searchAfter(query.getSearchAfter().stream().map(Object::toString).collect(Collectors.toList()));
+							}
+
+							query.getRescorerQueries().forEach(rescorerQuery -> {
+								bb.rescore(getRescore(rescorerQuery));
+							});
+
+							if (!query.getRuntimeFields().isEmpty()) {
+
+								Map<String, List<RuntimeField>> runtimeMappings = new HashMap<>();
+								query.getRuntimeFields().forEach(runtimeField -> {
+									runtimeMappings.put(runtimeField.getName(), Collections.singletonList(RuntimeField.of(rt -> rt //
+											.type(RuntimeFieldType._DESERIALIZER.parse(runtimeField.getType())) //
+											.script(s -> s.inline(is -> is.source(runtimeField.getScript()))))));
+								});
+								bb.runtimeMappings(runtimeMappings);
+							}
+
+							if (!isEmpty(query.getIndicesBoost())) {
+								Map<String, Double> boosts = new LinkedHashMap<>();
+								query.getIndicesBoost().forEach(indexBoost -> {
+									boosts.put(indexBoost.getIndexName(), (double) indexBoost.getBoost());
+								});
+								// noinspection unchecked
+								bb.indicesBoost(boosts);
+							}
+
+							if (query instanceof NativeQuery) {
+								prepareNativeSearch((NativeQuery) query, bb);
+							}
+							return bb;
+						} //
 				) //
 				);
+
 			});
+
 			return mrb;
 		});
 	}
 
+
 	private <T> void prepareSearchRequest(Query query, @Nullable Class<T> clazz, IndexCoordinates indexCoordinates,
 			SearchRequest.Builder builder, boolean forCount, boolean useScroll) {
 
@@ -1225,6 +1320,16 @@ private void addHighlight(Query query, SearchRequest.Builder builder) {
 		builder.highlight(highlight);
 	}
 
+	private void addHighlight(Query query, MultisearchBody.Builder builder) {
+
+		Highlight highlight = query.getHighlightQuery()
+			.map(highlightQuery -> new HighlightQueryBuilder(elasticsearchConverter.getMappingContext())
+				.getHighlight(highlightQuery.getHighlight(), highlightQuery.getType()))
+			.orElse(null);
+
+		builder.highlight(highlight);
+	}
+
 	private List<SortOptions> getSortOptions(Sort sort, @Nullable ElasticsearchPersistentEntity<?> persistentEntity) {
 		return sort.stream().map(order -> getSortOptions(order, persistentEntity)).collect(Collectors.toList());
 	}
@@ -1289,6 +1394,7 @@ private SortOptions getSortOptions(Sort.Order order, @Nullable ElasticsearchPers
 		}
 	}
 
+	@SuppressWarnings("DuplicatedCode")
 	private void prepareNativeSearch(NativeQuery query, SearchRequest.Builder builder) {
 
 		query.getScriptedFields().forEach(scriptedField -> {
@@ -1307,6 +1413,25 @@ private void prepareNativeSearch(NativeQuery query, SearchRequest.Builder builde
 		// todo #2150 searchExt, currently not supported by the new client
 	}
 
+	@SuppressWarnings("DuplicatedCode")
+	private void prepareNativeSearch(NativeQuery query, MultisearchBody.Builder builder) {
+
+		query.getScriptedFields().forEach(scriptedField -> {
+			builder.scriptFields(scriptedField.getFieldName(), sf -> sf.script(getScript(scriptedField.getScriptData())));
+		});
+
+		builder //
+			.suggest(query.getSuggester()) //
+			.collapse(query.getFieldCollapse()) //
+		;
+
+		if (!isEmpty(query.getAggregations())) {
+			builder.aggregations(query.getAggregations());
+		}
+
+		// todo #2150 searchExt, currently not supported by the new client
+	}
+
 	@Nullable
 	private co.elastic.clients.elasticsearch._types.query_dsl.Query getQuery(@Nullable Query query,
 			@Nullable Class<?> clazz) {