How does PlatformTransactionManager transactionManager(EntityManagerFactory emf) work?

Question

Java

Good day everyone! I switched from xml configuration to java config, everything works fine, only misunderstanding of one thing torments me: When I create:

public PlatformTransactionManager transactionManager(EntityManagerFactory emf)

then there is a reference to the EntityManagerFactory emf in the method arguments. In xml, when I did transactionManager, it referred to the factory, here, as I understand it, the same thing happens, but apparently I have a small gap in knowledge, because I did similar things, but I also did not understand at what point the object was created, is picked up, i.e. I feel, but I do not see an obvious connection. Maybe, if in this example all the beans are singletons, when the context is raised, it matches them?
Below is the complete code:

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.JpaVendorAdapter;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

import javax.persistence.EntityManagerFactory;
import java.util.Properties;

@Configuration
@ComponentScan("com.springapp.mvc")
@EnableWebMvc
@EnableTransactionManagement
public class MvcConfiguration extends WebMvcConfigurerAdapter {


    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/**").addResourceLocations("/");
    }

    @Bean(name = "dataSource")
    public DriverManagerDataSource dataSource() {
        DriverManagerDataSource driverManagerDataSource = new DriverManagerDataSource();
        driverManagerDataSource.setDriverClassName("com.mysql.jdbc.Driver");
        driverManagerDataSource.setUrl("jdbc:mysql://127.0.0.1:3306/mydbtest?useSSL=false");
        driverManagerDataSource.setUsername("root");
        driverManagerDataSource.setPassword("root");

        return driverManagerDataSource;
    }

    @Bean(name = "entityManagerFactory")
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(){
        LocalContainerEntityManagerFactoryBean EMFactory = new LocalContainerEntityManagerFactoryBean();
        EMFactory.setDataSource(dataSource());
        EMFactory.setPackagesToScan("com.springapp.mvc.Entities");

        JpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        EMFactory.setJpaVendorAdapter(vendorAdapter);
        EMFactory.setJpaProperties(additionalProperties());

        return EMFactory;
    }


    Properties additionalProperties() {
        Properties properties = new Properties();
        properties.setProperty("hibernate.hbm2ddl.auto", "update");
        properties.setProperty("hibernate.dialect", "org.hibernate.dialect.MySQL5Dialect");

        return properties;
    }

    @Bean(name = "transactionManager")
    public PlatformTransactionManager transactionManager(EntityManagerFactory emf){
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(emf);

        return transactionManager;
    }

    @Bean
    public PersistenceExceptionTranslationPostProcessor exceptionTranslation(){
        return new PersistenceExceptionTranslationPostProcessor();
    }

}