JPA Bidirectional relationship throws java.lang.StackOverflowError: null

i'm trying to relate two entities with JPA, when i run the project don't throws me errors but when i request the method that get me the Voters of a Comunity Leader i get the next Exception:

java.lang.StackOverflowError: null
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245) ~[gson-2.8.5.jar:na]
at com.google.gson.Gson$FutureTypeAdapter.write(Gson.java:1018) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:97) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:61) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245) ~[gson-2.8.5.jar:na]
at com.google.gson.Gson$FutureTypeAdapter.write(Gson.java:1018) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:97) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:61) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127) ~[gson-2.8.5.jar:na]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245) ~[gson-2.8.5.jar:na]
at com.google.gson.Gson$FutureTypeAdapter.write(Gson.java:1018) ~[gson-2.8.5.jar:na]

I'ts like a loop, i don't khow how to resolve this.

Here are my classes:

1)Leader Entity :

@Entity
@Table(name = "leaders")
public class Leader implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    Long id;

    @NotEmpty
    String phone;

    @NotEmpty
    String name;

    @OneToMany( mappedBy = "leader", fetch = FetchType.LAZY,cascade = CascadeType.ALL, orphanRemoval = true)
    private List<Voter> voters;



    public Leader() {
        voters = new ArrayList<>();
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getCelular() {
        return phone;
    }

    public void setCelular(String celular) {
        this.phone = celular;
    }

    public String getNombre() {
        return name;
    }

    public void setNombre(String nombre) {
        this.name = nombre;
    }

    public List<Voter> getVotantes() {
        return voters;
    }

    public void setVotantes(List<Voter> votantes) {
        this.voters = votantes;
    }

    public void addVotante(Voter votante){
        voters.add(votante);
    }
}

2)Voter Entity :

@Entity
@Table(name = "voters")
public class Voter implements Serializable {

    @Id
    String id;

    String name;

    String phone;

    String email;

    @Column(name = "electoral_school")
    String electoralSchool;

    @Temporal(TemporalType.DATE)
    Date registrationDate;

    @ManyToOne(fetch = FetchType.LAZY)
    private Leader leader;

    @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    Sector sector;

    @PrePersist
    public void prePersist() {
        registrationDate = new Date();
    }


    public String getCedula() {
        return id;
    }

    public void setCedula(String cedula) {
        this.id = cedula;
    }

    public String getNombre() {
        return name;
    }

    public void setNombre(String nombre) {
        this.name = nombre;
    }

    public String getTelefono() {
        return phone;
    }

    public void setTelefono(String telefono) {
        this.phone = telefono;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getColegioElectoral() {
        return electoralSchool;
    }

    public void setColegioElectoral(String colegioElectoral) {
        this.electoralSchool = colegioElectoral;
    }

    public Leader getDirigente() {
        return leader;
    }

    public void setDirigente(Leader dirigente) {
        this.leader = dirigente;
    }

    public Date getRegistro() {
        return registrationDate;
    }

    public void setRegistro(Timestamp registro) {
        this.registrationDate = registro;
    }
}

3)LeaderController :

@Controller
@RequestMapping("/leader")
public class LeaderController {

    @Autowired
    IDirigenteService leaderService;

    @RequestMapping(value="getVoters/{leader_id}")
    @ResponseBody
    public String getAll(@PathVariable(value = "leader_id") Long leader_id){
        Gson gson = new Gson();
        return gson.toJson(leaderService.findById(leader_id).getVotantes());

    }

}

I fill the tables with test data in import.sql.

Thanks in advance.

Hibernate OneToMany or JPA Bidirectional relationship throws java.lang.StackOverflowError: null is a Circular dependency issue that can originate from Lombok's toString() autogenerated method if you use @Data complex annotation.

To exclude your circular dependency for a certain field or better still, you use @Getter and @Setter if you do not need the toString(). Well, when I had those issues above these solutions worked for me.

You may then use the @JsonIgnore on the particular attribute.

@Getter

@Setter

public class MyClass {

}