Connection to one from two Identical databases in Spring boot application at RUNTIME

UPDATED

I'm getting an issue with Spring framework while I try to connect to 2 identical databases (with same tables) and then choose one of them to make requests. I'm using for this, 3 config files DbConfig, AbstractRoutingDataSource and an application.properties file. I'm currently not getting any ERRORS, while starting my application, but any time I use my restful webservice I get empty data, check the controller file below.

NOTE: I've followed all these links and still no results:

1. Baeldung AbstractRoutingDataSource guide
2. Alexander guide
3. Dynamic DataSource Routing on Spring website

I'm working on Spring boot v2.0.5.

NOTE: please do NOT answer me if you don't have any ideas about AbstractRoutingDataSource class and how it works.

My application.properties file

spring.jpa.database=mysql
spring.jpa.open-in-view=false

# Main database DEV_database1 
first.datasource.url = jdbc:mysql://localhost:3306/DEV_database1 
first.datasource.username = root 
first.datasource.password =  
first.datasource.driver-class-name = com.mysql.jdbc.Driver

# second database DEV_database2 
second.datasource.url = jdbc:mysql://localhost:3306/DEV_database2 
second.datasource.username = root 
second.datasource.password =  
second.datasource.driver-class-name = com.mysql.jdbc.Driver

spring.jpa.database-platform = org.hibernate.dialect.H2Dialect
spring.jpa.show-sql = true
spring.jpa.hibernate.naming.implicit-strategy=org.hibernate.boot.model.naming.ImplicitNamingStrategyLegacyJpaImpl
spring.jpa.hibernate.naming.physical-strategy=org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl
#...

[UPDATE] My DbConfig file

@Configuration
public class DbConfig {

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

    @Bean
    @Primary
    public HikariDataSource firstDataSource() {
        return firstDataSourceProperties().initializeDataSourceBuilder().type(HikariDataSource.class).build();
    }

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

    @Bean
    public HikariDataSource secondDataSource() {
        return secondDataSourceProperties().initializeDataSourceBuilder().type(HikariDataSource.class).build();
    }   

    @Bean
    DataSource dataSources() {

        AbstractRoutingDataSource dataSource = new CustomerRoutingDataSource();

        Map<Object, Object> resolvedDataSources = new HashMap<>();    
        resolvedDataSources.put(DbType.DATASOURCE1, firstDataSource());
        resolvedDataSources.put(DbType.DATASOURCE2, secondDataSource());

        dataSource.setDefaultTargetDataSource(firstDataSource()); // << default
        dataSource.setTargetDataSources(resolvedDataSources);
        return dataSource;
    }   
}

My CustomerRoutingDataSource.java

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
/**
 * AbstractRoutingDatasource can be used in place of standard DataSource implementations and enables a mechanism to
 * determine which concrete DataSource to use for each operation at runtime.
 * 
 * @author fre
 */
public class CustomerRoutingDataSource extends AbstractRoutingDataSource {

    private static final Logger log = LoggerFactory.getLogger(CustomerRoutingDataSource.class);

    @Override
    protected Object determineCurrentLookupKey() {
        log.info(">>> determineCurrentLookupKey thread: {}", Thread.currentThread().getName() );
        log.info(">>> RoutingDataSource: {}", DbContextHolder.getDbType());
        return DbContextHolder.getDbType();
    }
}

My DbContextHolder.java

public class DbContextHolder {

       private static final ThreadLocal<DbType> contextHolder =
                new ThreadLocal<DbType>();
       // set the datasource
       public static void setDbType(DbType dbType) {
           if(dbType == null){
               throw new NullPointerException();
           }
          contextHolder.set(dbType);
       }
       // get the current datasource in use
       public static DbType getDbType() {
          return (DbType) contextHolder.get();
       }
       // clear datasource
       public static void clearDbType() {
          contextHolder.remove();
       }
}

DbType.java

public enum DbType {
    DATASOURCE1, 
    DATASOURCE2,
}

This is how I'm using it in Controller:

My Controller

@RestController
@RequestMapping("/api/user")
public class MembreController extends MainController {

    @Autowired
    MembreRepository membreRepository;

    @GetMapping("/login")
    public ResponseString login(String userName, String password) {

        // setting the datasouce to DATASOURCE1
        DbContextHolder.setDbType(DbType.DATASOURCE1);

        // finding the list of user in DataSource1
        List<Membres> list = membreRepository.findAll();

        // clearing the current datasource
        DbContextHolder.clearDbType();

        for (Iterator<Membres> membreIter = list.iterator(); membreIter.hasNext();) {
            Membres membre = membreIter.next();

            if (membre.getUserName().equals(userName) && membre.getPassword().equals(password)) {
                return new ResponseString("Welcome" + membre.getFirstName() + " " + membre.getLastName());
            }
        }
        return new ResponseString("User not found");
    }

}

my Application.java file

@ComponentScan
@SpringBootApplication
public class Application extends SpringBootServletInitializer {

    /**
     * main method
     * 
     * @param args
     */
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }


    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(Application.class);
    }

}