Configured two data source in spring data JPA but second data source still considering first DB URL

In this official example of configuring 2 data sources, they have used embedded DB. So, with the help of Spring boot's How to documentations, Configure Two DataSources and Using Multiple EntityManagerFactories, I customized that to use MySQL DB.

You can find the complete code under this Github repository. Don't forget to checkout the "two_data_sources_in_separate_files" branch.

But with this modification, "secondDBTransactionManager" is not pointing second_db. Instead, it is inserting data into first_db.

FirstDataSource.java

@Configuration
@EnableJpaRepositories(entityManagerFactoryRef = "firstDBEntityManagerFactory", transactionManagerRef = "firstDBTransactionManager")

public class FirstDataSource {
@Bean
PlatformTransactionManager firstDBTransactionManager(DataSourceProperties firstDataSourceProperties) {
    return new JpaTransactionManager(firstDBEntityManagerFactory(firstDataSourceProperties).getObject());
}

@Bean
@Primary
LocalContainerEntityManagerFactoryBean firstDBEntityManagerFactory(DataSourceProperties firstDataSourceProperties) {

    HibernateJpaVendorAdapter jpaVendorAdapter = new HibernateJpaVendorAdapter();
    jpaVendorAdapter.setGenerateDdl(true);

    LocalContainerEntityManagerFactoryBean factoryBean = new LocalContainerEntityManagerFactoryBean();

    factoryBean.setDataSource(firstDS(firstDataSourceProperties));
    factoryBean.setJpaVendorAdapter(jpaVendorAdapter);
    factoryBean.setPackagesToScan(FirstDataSource.class.getPackage().getName());

    return factoryBean;
}

@Bean
@Primary
@ConfigurationProperties("app.datasource.first")
public DataSourceProperties firstDataSourceProperties() {
    return new DataSourceProperties();
}

@Bean
@Primary
@ConfigurationProperties("app.datasource.first.configuration")
public HikariDataSource firstDS(DataSourceProperties firstDataSourceProperties) {
    return firstDataSourceProperties.initializeDataSourceBuilder().type(HikariDataSource.class).build();
}

}

SecondDataSource.java

@Configuration
@EnableJpaRepositories(entityManagerFactoryRef = "secondDBEntityManagerFactory", transactionManagerRef = "secondDBTransactionManager")
public class SecondDataSource {

@Bean
PlatformTransactionManager secondDBTransactionManager(DataSourceProperties secondDataSourceProperties) {
    return new JpaTransactionManager(secondDBEntityManagerFactory(secondDataSourceProperties).getObject());
}

@Bean
@ConfigurationProperties("app.datasource.second")
public DataSourceProperties secondDataSourceProperties() {
    return new DataSourceProperties();
}

@Bean
@ConfigurationProperties("app.datasource.second.configuration")
public HikariDataSource secondDS(
        @Qualifier("secondDataSourceProperties") DataSourceProperties secondDataSourceProperties) {
    return secondDataSourceProperties.initializeDataSourceBuilder().type(HikariDataSource.class).build();
}

@Bean
public LocalContainerEntityManagerFactoryBean secondDBEntityManagerFactory(DataSourceProperties secondDataSourceProperties) {
    HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
    vendorAdapter.setGenerateDdl(true);

    LocalContainerEntityManagerFactoryBean factoryBean = new LocalContainerEntityManagerFactoryBean();
    factoryBean.setDataSource(secondDS(secondDataSourceProperties));
    factoryBean.setJpaVendorAdapter(vendorAdapter);
    factoryBean.setPackagesToScan(SecondDataSource.class.getPackage().getName());

    return factoryBean;
}

}

FetchData.java

@Controller // This means that this class is a Controller
@RequestMapping(path = "/demo") // This means URL's start with /demo (after Application path)
public class FetchData {

@Autowired
private TableARepository tableARepository;

@Autowired
private TableCRepository tableCRepository;

@GetMapping(path = "/addDataToFirstDB")
public @ResponseBody void addDataToFirstDB() {
    // This returns a JSON or XML with the users
    Table_A tableA = new Table_A();
    tableA.setTable_a_col_1("test1");
    tableA.setTable_a_col_2("test2");
    tableA.setTable_a_col_3("test3");
    tableA.setTable_a_col_4("test4");
    
    System.out.println("Inserting data into first DB.");
    tableARepository.save(tableA);
    
}

@GetMapping(path = "/addDataToSecondDB")
@Transactional("secondDBTransactionManager")
public @ResponseBody void addDataToSecondDB() {
    // This returns a JSON or XML with the users
    Table_C tableC = new Table_C();
    tableC.setTable_c_col_1("test1");
    tableC.setTable_c_col_2("test2");
    tableC.setTable_c_col_3("test3");
    tableC.setTable_c_col_4("test4");
    
    System.out.println("Inserting data into second DB.");
    tableCRepository.save(tableC);
}
}

Observe that, I've used @Transactional("secondDBTransactionManager") for second REST API, "addDataToSecondDB". It is easy to resolve issue if any Exception is thrown. There is no Exception here but the behavior is not as expected.