ERROR: null value in column "id_municipio_id_municipio" violates the non-null restriction

Question

This error is occurring when I try to persist the screen data to the database. I checked, by debugging the screen, that the data is being captured. When the method exits line 33 of the image it goes straight to line 45.

the server log is like this:

org.postgresql.util.PSQLException: ERRO: valor nulo na coluna "id_municipio_id_municipio" viola a restrição não-nula
  Detalhe: Registro que falhou contém (22, 5462, null, yurhjfdn, 1, null, null).

Distritocontroller class

@RestController
@RequestMapping(value="/user")
public class DistritosController {

    @Autowired
    DistritosService distritosService; 


    @RequestMapping(method = RequestMethod.POST, value = "/distritos", consumes = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<Distritos> cadastrarDistritos(@RequestBody Distritos distritos) {
        Distritos distritosCadastrado = distritosService.cadastrar(distritos);
        return new ResponseEntity<Distritos>(distritosCadastrado, HttpStatus.CREATED);
    }

    @RequestMapping(method = RequestMethod.GET, value = "/distritos", produces = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<Collection<Distritos>> buscarTodosDistritos() {
        Collection<Distritos> distritosBuscados = distritosService.buscarTodos();
        return new ResponseEntity<>(distritosBuscados, HttpStatus.OK);
    }

    @RequestMapping(method = RequestMethod.GET, value = "/distritos/{id}", produces = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<Distritos> buscarDistritosPorId(@PathVariable int id) {
        Distritos distritos = distritosService.buscaPorId(id);
        return new ResponseEntity<>(distritos, HttpStatus.OK);
    }

    @RequestMapping(method = RequestMethod.DELETE, value = "/distritos/{id}")
    public ResponseEntity<Distritos> excluirDistritos(@PathVariable int id) {
        Distritos distritoEncontrado = distritosService.buscaPorId(id);
        if (distritoEncontrado == null) {
            return new ResponseEntity<>(HttpStatus.NOT_FOUND);
        }
        distritosService.excluir(distritoEncontrado);
        return new ResponseEntity<>(HttpStatus.OK);
    }

    @RequestMapping(method = RequestMethod.PUT, value = "/distritos", consumes = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<Distritos> alterarDistritos(@RequestBody Distritos distritos) {
        Distritos distritoAlterado = distritosService.alterar(distritos);
        return new ResponseEntity<Distritos>(distritoAlterado, HttpStatus.OK);
    }


}

Class Districts

@Entity
@Table(name = "distritos", schema="glb")
@XmlRootElement
@NamedQueries({
    @NamedQuery(name = "Distritos.findAll", query = "SELECT d FROM Distritos d"),
    @NamedQuery(name = "Distritos.findByIdDistrito", query = "SELECT d FROM Distritos d WHERE d.idDistrito = :idDistrito"),
    @NamedQuery(name = "Distritos.findByNome", query = "SELECT d FROM Distritos d WHERE d.nome = :nome"),
    @NamedQuery(name = "Distritos.findByCodigoDne", query = "SELECT d FROM Distritos d WHERE d.codigoDne = :codigoDne"),
    @NamedQuery(name = "Distritos.findByFlagAtivo", query = "SELECT d FROM Distritos d WHERE d.flagAtivo = :flagAtivo")})




@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "idDistrito", scope= Distritos.class)        
public class Distritos implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id_distrito")
    private Long idDistrito;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 70)
    @Column(name = "nome")
    private String nome;
    @Size(max = 8)
    @Column(name = "codigo_dne")
    private String codigoDne;
    @Column(name = "flag_ativo")
    private Integer flagAtivo;
    @JoinColumn()
    @ManyToOne
    private Entidades idEntidade;
    @JoinColumn()
    @ManyToOne(optional = false)
    private Municipios idMunicipio;
    @JoinColumn()
    @ManyToOne(optional = false)
    private Ufs idUf;

    public Distritos() {
    }

   gets and sets . ..

}

Classe Municipios

@Entity
@Table(name = "municipios", schema="glb")
@XmlRootElement
@NamedQueries({
    @NamedQuery(name = "Municipios.findAll", query = "SELECT m FROM Municipios m"),
    @NamedQuery(name = "Municipios.findByIdMunicipio", query = "SELECT m FROM Municipios m WHERE m.idMunicipio = :idMunicipio"),
    @NamedQuery(name = "Municipios.findByCep", query = "SELECT m FROM Municipios m WHERE m.cep = :cep"),
    @NamedQuery(name = "Municipios.findByCodigoDne", query = "SELECT m FROM Municipios m WHERE m.codigoDne = :codigoDne"),
    @NamedQuery(name = "Municipios.findByCodigoIbge", query = "SELECT m FROM Municipios m WHERE m.codigoIbge = :codigoIbge"),
    @NamedQuery(name = "Municipios.findByFlagAtivo", query = "SELECT m FROM Municipios m WHERE m.flagAtivo = :flagAtivo"),
    @NamedQuery(name = "Municipios.findByNome", query = "SELECT m FROM Municipios m WHERE m.nome = :nome")})

@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "idMunicipio", scope= Municipios.class)    
public class Municipios implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @Basic(optional = false)
    @NotNull
    private Long idMunicipio;
    @Size(max = 8)
    private String cep;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 8)
    private String codigoDne;
    @Size(max = 7)
    private String codigoIbge;
    private Integer flagAtivo;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 72)
    private String nome;


    @JoinColumn()
    @ManyToOne(optional = false)
    private Ufs idUf;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "idMunicipio")


    private Collection<Bairros> bairrosCollection;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "idMunicipio")
    private Collection<PessoasEnderecos> pessoasEnderecosCollection;


    @OneToMany(cascade = CascadeType.ALL, mappedBy = "idMunicipio")
    private Collection<Logradouros> logradourosCollection;


    @OneToMany(cascade = CascadeType.ALL, mappedBy = "idMunicipio")
    private Collection<Entidades> entidadesCollection;

    public Municipios() {
    }

gets and sets ... 


}

ufs class

@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "idUf", scope= Ufs.class)  
public class Ufs implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @Basic(optional = false)
    @NotNull
    private Long idUf;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 2)
    private String codigoDne;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 72)
    private String nome;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 2)
    private String sigla;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "idUf")
    private Collection<Municipios> municipiosCollection;
    @JoinColumn()
    @ManyToOne(optional = false)
    private Paises idPais;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "idUf")
    private Collection<PessoasEnderecos> pessoasEnderecosCollection;

    public Ufs() {
    }

gets and sets ... 

}