@Entity
    @Table(name = "app_cluster", uniqueConstraints = {
    @UniqueConstraint(columnNames = {"clustercode"})})
    @NamedQueries({
    @NamedQuery(name = "AppCluster.findAll", query = "SELECT a FROM AppCluster a")})

    public class AppCluster implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id", nullable = false)
    private Long id;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 150)
    @Column(name = "clustercode", nullable = false, length = 150)
    private String clustercode;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 150)
    @Column(name = "clustername", nullable = false, length = 150)
    private String clustername;

    @OneToMany(cascade = CascadeType.ALL)
    @JoinColumn(name = "clusterid", referencedColumnName="id", nullable = false)
    private Set<AppAgency> clusterAgency = new HashSet<>();
    ....<Getters and Setters>

@Entity
    @Table(name = "app_agency", uniqueConstraints = {
    @UniqueConstraint(columnNames = {"agencycode"})})
    @NamedQueries({
    @NamedQuery(name = "AppAgency.findAll", query = "SELECT a FROM AppAgency a")})
    public class AppAgency implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id", nullable = false)
    private Long id;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 150)
    @Column(name = "agencycode", nullable = false, length = 150)
    private String agencycode;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 150)
    @Column(name = "agencyname", nullable = false, length = 150)
    private String agencyname;
    @Basic(optional = false)
    @NotNull
    @Column(name = "clusterid", nullable = false)
    private long clusterid;

Map<String, String> settings = new HashMap<>();
        settings.put("hibernate.connection.driver_class", "com.mysql.cj.jdbc.Driver");
        settings.put("hibernate.connection.url", "jdbc:mysql://localhost:3306/onetomanytest");
        settings.put("hibernate.connection.username", "root");
        settings.put("hibernate.connection.password", "root");
        settings.put("hibernate.show_sql", "true");
        //settings.put("hibernate.hbm2ddl.auto", "update");
        settings.put("hibernate.hbm2ddl.auto", "create");

        registry = registryBuilder.applySettings(settings).build();

        MetadataSources sources = new MetadataSources(registry)
              .addAnnotatedClass(AppCluster.class)
              .addAnnotatedClass(AppAgency.class);

session = HibernateUtil.getSessionFactory().openSession();
     transaction = session.getTransaction();
     transaction.begin();

     AppCluster cluster1 = new AppCluster();
     cluster1.setClustercode("clustercode1");
     cluster1.setClustername("clustername1");

     AppAgency agency1 = new AppAgency();
     agency1.setAgencycode("agencycode1");
     agency1.setAgencyname("agencyname1");
     agency1.setClusterid(cluster1.getId());

     //cluster1.getClusterAgency().add(agency1);


     //session.persist(agency1);
     session.persist(cluster1);

SessionFactory creation failed
Mar 22, 2018 9:56:38 AM org.hibernate.service.internal.AbstractServiceRegistryImpl stopService
INFO: HHH000369: Error stopping service [class org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl] : java.lang.NullPointerException
java.lang.NullPointerException
    at com.springmvc.hibernate.MainApp.main(MainApp.java:15)