É a minha primeira pergunta aqui na pilha, então por favor seja gentil: D

Eu estou tentando criar uma relação de OneToMany de hibernação. Quando tento buscar alguns dados do meu banco de dados, estou obtendo StackOverflowError. Mas quando eu removo a parte OneToMany, tudo corre normalmente. Isso faz parte do meu serviço REST, por enquanto ele é executado no VMware vFabric Server e MySQL DB.

Exemplo de busca:

@Inject
private EntityManager entityManager;
...
entityManager.find(League.class, 1);
...
entityManager.find(Team.class, 1);

Script do MySQL:

CREATE TABLE league (
    id int(11) NOT NULL AUTO_INCREMENT,
    name varchar(20) COLLATE utf8_unicode_ci NOT NULL,
    PRIMARY KEY (id)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

CREATE TABLE team (
    team_id int(11) NOT NULL AUTO_INCREMENT,
    name varchar(20) COLLATE utf8_unicode_ci NOT NULL,
    fk_leagueId int(11) NOT NULL,
    PRIMARY KEY (team_id),
    FOREIGN KEY (fk_leagueId) REFERENCES league(id)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

Classes:

@XmlRootElement
@Entity
@Table(name = "team")
@Data
public class Team {
    @Id
    @GeneratedValue(generator = "increment")
    @GenericGenerator(name = "increment", strategy = "increment")
    @Column(name = "team_id")
    private int id;
    @Column(name = "name")
    private String name;
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "fk_leagueId", nullable = false)
    private League league;
}

@XmlRootElement
@Entity
@Table(name = "league")
@Data
public class League {
    @Id
    @GeneratedValue(generator = "increment")
    @GenericGenerator(name = "increment", strategy = "increment")
    @Column(name = "id")
    private int id;
    @Column(name = "name")
    private String name;
    //if I comment 2 lines below, there is no error, and everything works fine
    @OneToMany(fetch = FetchType.LAZY, mappedBy = "league")
    private Set<span><</span>Team> teams;
}

Erro:

Hibernate: select league0_.id as id1_1_0_, league0_.name as name2_1_0_ from league league0_ where league0_.id=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Hibernate: select teams0_.fk_leagueId as fk3_1_1_, teams0_.team_id as team1_4_1_, teams0_.team_id as team1_4_0_, teams0_.fk_leagueId as fk3_4_0_, teams0_.name as name2_4_0_ from team teams0_ where teams0_.fk_leagueId=?
Exception in thread "tomcat-http--3" java.lang.StackOverflowError
    at org.jboss.logging.JDKLogger.translate(JDKLogger.java:73)
    at org.jboss.logging.JDKLogger.isEnabled(JDKLogger.java:85)
    at org.jboss.logging.JDKLogger.doLog(JDKLogger.java:41)
    at org.jboss.logging.Logger.debug(Logger.java:406)
    at org.hibernate.internal.CoreMessageLogger_$logger.debug(CoreMessageLogger_$logger.java:525)
    at org.hibernate.engine.jdbc.spi.SqlStatementLogger.logStatement(SqlStatementLogger.java:104)
    at org.hibernate.engine.jdbc.spi.SqlStatementLogger.logStatement(SqlStatementLogger.java:95)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:180)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:159)
    at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1858)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1835)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1815)
    at org.hibernate.loader.Loader.doQuery(Loader.java:899)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:341)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:311)
    at org.hibernate.loader.Loader.loadCollection(Loader.java:2234)
    at org.hibernate.loader.collection.CollectionLoader.initialize(CollectionLoader.java:65)
    at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:674)
    at org.hibernate.event.internal.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:83)
    at org.hibernate.internal.SessionImpl.initializeCollection(SessionImpl.java:1849)
    at org.hibernate.collection.internal.AbstractPersistentCollection$4.doWork(AbstractPersistentCollection.java:549)
    at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:234)
    at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:545)
    at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:124)
    at org.hibernate.collection.internal.PersistentSet.hashCode(PersistentSet.java:428)
    at com.lukaszb.motspe.webapp.model.League.hashCode(League.java:21)
    at com.lukaszb.motspe.webapp.model.Team.hashCode(Team.java:20)
    at java.util.HashMap.hash(HashMap.java:351)
    at java.util.HashMap.put(HashMap.java:471)
    at java.util.HashSet.add(HashSet.java:217)
...

Editar:

Consegui resolver isso graças a @Thihara e @KarIP. Eu anulei toString () para Team e League assim:

@Override
public String toString() {
    return "League [id=" + id + ", name=" + name + "]";
}

@Override
public String toString() {
    return "Team [id=" + id + ", name=" + name + "]";
}

e foi capaz de buscar dados do banco de dados conforme desejado. Mas então, durante a análise, recebi o erro JAXB com ciclos infinitos. Então eu anotei a classe Team e League com@XmlAccessorType(XmlAccessType.FIELD), então não vai olhar para métodos, e equipeleague campo como@XmlTransient, por isso não será analisado.

Aqui eu posso até remover minhas implementações toString (), e ainda funciona. Eu não estou completamente certo do porquê. O problema está resolvido, mas gostaria de ouvir explicações mais precisas. Eu não sei porque o JAXB parou a busca de dados, mesmo que seja depois de todo o processo de comunicação do banco de dados (ou não é?). Para ser mais específico, estou usando Jersey para isso:

@GET
@Path("search/id")
@Produces({ MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML })
public List<League> searchById(@QueryParam("id") int id) {
return Arrays.asList(leagueDAO.getById(id));
}