Spring Boot REST endpoint seems to not execute Neo4j Java driver statements (JHipster + Neo4jConfig + Neo4jService) → no Cypher run

I am integrating Neo4j into my JHipster 8.5.0 / Spring Boot 3.3.0 application. I have configured a Neo4jConfig with a Driver bean, a Neo4jService to send Cypher statements, and a REST endpoint /api/neo4j/import that calls this service.

→ The REST endpoint returns 200 OK. → Neo4jService is initialized (driver injected). → But inside executeCypherStatements(), I never see the expected "Executing Cypher" logs. → Also, no Cypher statements appear in Neo4j.

I added catch blocks but no exception is thrown either. Neo4j Desktop is running, bolt://localhost:7687 is up, and the driver connects (driver initialized).

I am using the official neo4j-java-driver version 5.11.0 (not the Spring Boot starter).

→ Why is my service not executing the Cypher? → Is this a limitation of using neo4j-java-driver in JHipster / Spring Boot? → Do I need to switch to spring-boot-starter-data-neo4j to make it work properly?

1- ** I created a Neo4jConfig:**

@Configuration
public class Neo4jConfig {
    @Value("${neo4j.uri}")
    private String uri;

    @Value("${neo4j.username}")
    private String username;

    @Value("${neo4j.password}")
    private String password;

    @Bean
    public Driver neo4jDriver() {
        return GraphDatabase.driver(uri, AuthTokens.basic(username, password));
    }
}

2- ** I created a Neo4jService:**

@Service
public class Neo4jService {
    private final Driver driver;

    public Neo4jService(Driver driver) {
        this.driver = driver;
        System.out.println("Neo4jService initialized with driver: " + driver);
    }

    @PostConstruct
    public void postConstruct() {
        System.out.println("Neo4jService postConstruct - driver: " + driver);
    }

    public void executeCypherStatements(List<String> statements) {
        try (Session session = driver.session()) {
            System.out.println("Neo4jService → session opened");  // I added this
            for (String stmt : statements) {
                System.out.println("Executing Cypher: " + stmt);
                session.run(stmt);
            }
        } catch (Exception e) {
            System.out.println("Neo4jService ERROR → " + e.getMessage());
            e.printStackTrace();
        }
    }
}

3- ** I created a REST controller:**

@RestController
@RequestMapping("/api/neo4j")
public class Neo4jImportResource {
    private final Neo4jService neo4jService;

    @Autowired
    public Neo4jImportResource(Neo4jService neo4jService) {
        this.neo4jService = neo4jService;
    }

    @PostMapping("/import")
    public ResponseEntity<String> importGraph() {
        List<String> statements = List.of(
            "MERGE (a:TestNode {name: 'NodeA'})",
            "MERGE (b:TestNode {name: 'NodeB'})",
            "MERGE (a)-[:CONNECTED_TO]->(b)"
        );

        neo4jService.executeCypherStatements(statements);

        return ResponseEntity.ok("Import done");
    }
}

4- In my application-dev.yml I configured:

neo4j:
  uri: bolt://localhost:7687
  username: neo4j
  password: mypassword

5- Result:

I can see in backend console:

Neo4jService initialized with driver: org.neo4j.driver.internal.InternalDriver@xxxx
Neo4jService postConstruct, driver: org.neo4j.driver.internal.InternalDriver@xxxx

When I POST /api/neo4j/import I get HTTP 200 OK.

BUT I do NOT see:

Neo4jService → session opened
Executing Cypher: ...

→ It seems that executeCypherStatements() is not really executing → or that driver.session() fails silently.

6- Context Neo4j Desktop is started, with base neo4j running on port 7687.

The driver does connect (since driver is initialized).

No exception printed in catch block → but nothing runs.

JHipster project (so I use Gradle and neo4j-java-driver 5.11.0, not spring-boot-starter-data-neo4j).

7- Question:

• Why is my Neo4jService.executeCypherStatements() apparently not running?
• Why does session.run() produce no log / no exception but also no Cypher in Neo4j?
• Is this a problem with neo4j-java-driver used inside JHipster / Spring Boot? Do I need spring-boot-starter-data-neo4j instead?

→ Any advice welcome, I just want to inject Cypher statements reliably from my REST controller.

Thanks in advance!