DATAES-832 - findAllById repository method returns iterable with null elements for not found ids.

#Original PR: spring-projects#460

Author: sothawo

src/main/java/org/springframework/data/elasticsearch/repository/support/SimpleElasticsearchRepository.java

@@ -19,6 +19,7 @@
 
 import java.util.Collections;
 import java.util.List;
+import java.util.Objects;
 import java.util.Optional;
 import java.util.stream.Collectors;
 
@@ -153,8 +154,8 @@ public Iterable<T> findAll(Sort sort) {
 	public Iterable<T> findAllById(Iterable<ID> ids) {
 		Assert.notNull(ids, "ids can't be null.");
 		NativeSearchQuery query = new NativeSearchQueryBuilder().withIds(stringIdsRepresentation(ids)).build();
-		// noinspection ConstantConditions
-		return execute(operations -> operations.multiGet(query, entityClass, getIndexCoordinates()));
+		return execute(operations1 -> operations1.multiGet(query, entityClass, getIndexCoordinates())).stream()
+				.filter(Objects::nonNull).collect(Collectors.toList());
 	}
 
 	@Override
@@ -214,7 +215,7 @@ public Iterable<T> search(QueryBuilder query) {
 		if (count == 0) {
 			return new PageImpl<>(Collections.emptyList());
 		}
-		searchQuery.setPageable(PageRequest.of(0, (int)count));
+		searchQuery.setPageable(PageRequest.of(0, (int) count));
 		SearchHits<T> searchHits = execute(
 				operations -> operations.search(searchQuery, entityClass, getIndexCoordinates()));
 		AggregatedPage<SearchHit<T>> page = SearchHitSupport.page(searchHits, searchQuery.getPageable());

src/test/java/org/springframework/data/elasticsearch/repository/support/simple/SimpleElasticsearchRepositoryTests.java

@@ -25,12 +25,14 @@
 import lombok.Data;
 import lombok.NoArgsConstructor;
 
+import java.io.IOException;
 import java.lang.Long;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
+import java.util.stream.Collectors;
 
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
@@ -56,6 +58,7 @@
 import org.springframework.data.elasticsearch.repository.ElasticsearchRepository;
 import org.springframework.data.elasticsearch.repository.config.EnableElasticsearchRepositories;
 import org.springframework.data.elasticsearch.utils.IndexInitializer;
+import org.springframework.data.util.StreamUtils;
 import org.springframework.test.context.ContextConfiguration;
 
 /**
@@ -361,6 +364,14 @@ public void shouldReturnResultsForGivenSearchQuery() {
 	@Test
 	public void shouldDeleteAll() {
 
+		// given
+		String documentId = randomNumeric(5);
+		SampleEntity sampleEntity = new SampleEntity();
+		sampleEntity.setId(documentId);
+		sampleEntity.setMessage("hello world.");
+		sampleEntity.setVersion(System.currentTimeMillis());
+		repository.save(sampleEntity);
+
 		// when
 		repository.deleteAll();
 
@@ -677,6 +688,32 @@ public void shouldNotFailOnIndexingEmptyList() {
 		assertThat(savedEntities).hasSize(0);
 	}
 
+	@Test // DATAES-832
+	void shouldNotReturnNullValuesInFindAllById() throws IOException {
+
+		// given
+		String documentId1 = "id-one";
+		SampleEntity sampleEntity1 = new SampleEntity();
+		sampleEntity1.setId(documentId1);
+		repository.save(sampleEntity1);
+		String documentId2 = "id-two";
+		SampleEntity sampleEntity2 = new SampleEntity();
+		sampleEntity2.setId(documentId2);
+		repository.save(sampleEntity2);
+		String documentId3 = "id-three";
+		SampleEntity sampleEntity3 = new SampleEntity();
+		sampleEntity3.setId(documentId3);
+		repository.save(sampleEntity3);
+
+		Iterable<SampleEntity> allById = repository
+				.findAllById(Arrays.asList("id-one", "does-not-exist", "id-two", "where-am-i", "id-three"));
+		List<SampleEntity> results = StreamUtils.createStreamFromIterator(allById.iterator()).collect(Collectors.toList());
+
+		assertThat(results).hasSize(3);
+		assertThat(results.stream().map(SampleEntity::getId).collect(Collectors.toList()))
+				.containsExactlyInAnyOrder("id-one", "id-two", "id-three");
+	}
+
 	private static List<SampleEntity> createSampleEntitiesWithMessage(String message, int numberOfEntities) {
 
 		List<SampleEntity> sampleEntities = new ArrayList<>();