GH-2791 - Support map with entity (list) as query parameter.

Closes #2791

Author: meistermeier

src/main/java/org/springframework/data/neo4j/repository/query/Neo4jQuerySupport.java

@@ -209,6 +209,11 @@ final Object convertParameter(Object parameter, @Nullable Neo4jPersistentPropert
 			return result;
 		}
 
+		if (parameter instanceof Map<?, ?> mapValue) {
+			return mapValue.entrySet().stream()
+					.collect(Collectors.toMap(Map.Entry::getKey, v -> convertParameter(v.getValue(), conversionOverride)));
+		}
+
 		return mappingContext.getConversionService().writeValue(parameter,
 				TypeInformation.of(parameter.getClass()), conversionOverride);
 	}

src/test/java/org/springframework/data/neo4j/integration/issues/IssuesIT.java

@@ -80,6 +80,7 @@
 import org.springframework.data.neo4j.integration.issues.gh2289.SkuRO;
 import org.springframework.data.neo4j.integration.issues.gh2289.SkuRORepository;
 import org.springframework.data.neo4j.integration.issues.gh2289.SkuRepository;
+import org.springframework.data.neo4j.integration.issues.gh2323.Knows;
 import org.springframework.data.neo4j.integration.issues.gh2323.Language;
 import org.springframework.data.neo4j.integration.issues.gh2323.Person;
 import org.springframework.data.neo4j.integration.issues.gh2323.PersonService;
@@ -533,6 +534,16 @@ void ensure1To1RelationshipsAreSerialized(@Autowired PersonService personService
 		});
 	}
 
+	@Test
+	@Tag("GH-2791")
+	void ensureMapOfRelationshipGetsSerialized(@Autowired PersonService personService) {
+		Knows knowsRelationship = new Knows("somedescription", new Language("German"));
+
+		Person person = personService.queryWithMapOfRelationship("someKey", knowsRelationship);
+
+		assertThat(person.getName()).isEqualTo("Helge");
+	}
+
 	@Test
 	@Tag("GH-2326")
 	void saveShouldAddAllLabels(@Autowired AnimalRepository animalRepository,

src/test/java/org/springframework/data/neo4j/integration/issues/gh2323/PersonRepository.java

@@ -16,6 +16,7 @@
 package org.springframework.data.neo4j.integration.issues.gh2323;
 
 import java.util.List;
+import java.util.Map;
 
 import org.springframework.data.neo4j.repository.Neo4jRepository;
 import org.springframework.data.neo4j.repository.query.Query;
@@ -28,7 +29,7 @@
 @Repository
 public interface PersonRepository extends Neo4jRepository<Person, String> {
 
-	// Using separate id and than relationships on top level
+	// Using separate id and then relationships on top level
 	@Query("""
 			UNWIND $relations As rel WITH rel
 			MATCH (f:Person {id: $from})
@@ -60,4 +61,12 @@ RETURN f, collect(r), collect(t)
 			RETURN f, frl, mt, collect(r), collect(t)
 			""")
 	Person updateRelWith11(@Param("person") Person person);
+
+	@Query("""
+			UNWIND keys($relationships) as relationshipKey
+			UNWIND $relationships[relationshipKey] as relationship
+			MATCH (p:Person)-[:HAS_MOTHER_TONGUE]->(:Language{name: relationship.__target__.__id__})
+			RETURN p
+			   """)
+	Person queryWithMapOfRelationship(@Param("relationships") Map<String, List<Knows>> relationshipList);
 }

src/test/java/org/springframework/data/neo4j/integration/issues/gh2323/PersonService.java

@@ -16,6 +16,7 @@
 package org.springframework.data.neo4j.integration.issues.gh2323;
 
 import java.util.List;
+import java.util.Map;
 import java.util.Optional;
 import java.util.stream.Collectors;
 
@@ -66,4 +67,8 @@ public Optional<Person> updateRel3(String id) {
 
 		return original;
 	}
+
+	public Person queryWithMapOfRelationship(String key, Knows knows) {
+		return personRepository.queryWithMapOfRelationship(Map.of(key, List.of(knows)));
+	}
 }