Spring boot RequestBody getting null

I'm new in Spring Boot, i have a little issue when i'm getting JSON in my RestController from Postman.

When i send the request from Postmat with its attributes it's always getting null in the RequestBody.

This is my Rest controller

@RestController
@RequestMapping(value="/api/enviar",produces = MediaType.APPLICATION_JSON_VALUE,
        headers = {"content-type=application/json"})
@RequiredArgsConstructor
@Slf4j
public class EnviarAdicionService {
    @Autowired
    private final EnviarAdicionUseCase enviarAdicionUseCase;
    @Autowired
    private final GuardarLogUseCase guardarLogUseCase;

    private final Gson gson = new Gson();
    private String _statusCode;
    private Date dateStart;


    @PostMapping
    public DatosAdicionResponse PostAdicionFondos(@RequestBody @Valid RequestAdicion requestAdicion){
          //PostMapping logic
          ...
    }
}

My RequestAdicion is like this:

@Data
@NoArgsConstructor
public class RequestAdicion implements Serializable {
    private final static String regExpression = "\\{\\[sw\\.,ñÑ]\\+\\$}";
    @RequestHeaderValidation
    private RequestHeader Header;
    @CuentaValidation(NumeroIdentificacionName = "NumeroDocumentoCuentaOrigen", TipoIdentificacionName = "TipoDocumentoCuentaOrigen",
            TipoCuentaDepositosName = "TipoCuentaDepositoOrigen", NumeroCuentaDepositoName = "NumeroCuentaDepositoOrigen",
            EntidadCuentaName = "EntidadCuentaOrigen", TipoCuentaName = "TipoCuentaOrigen", NumeroCuentaName = "NumeroCuentaOrigen",
            CodigoFondoName = "CodigoFondoCuentaOrigen", EntidadCuentaDepositoName = "EntidadCuentaDepositoOrigen")
    private CuentaOrigen CuentaOrigen;
    @CuentaFondoValidation(TipoIdentificacionName = "TipoDocumentoCuentaDestino", NumeroIdentificacionFondoName = "NumeroDocumentoCuentaDestino",
            EntidadName = "EntidadCuentaDestino", CodigoFondoName = "CodigoFondoCuentaDestino",
            NumeroFondoInversionName = "NumeroFondoInversionCuentaDestino")
    private CuentaFondo CuentaDestino;
    @FormaDePagoValidation
    @Pattern(regexp = regExpression,message = "Valor no permitido. FormaDePago")
    private String FormaDePago;
    @ValorValidation
    private double ValorAdicion;
    @OficinaValidation
    private long Oficina;
    @CanalValidation
    @Pattern(regexp = regExpression,message = "Valor no permitido. Canal")
    private String Canal;
}

I'm sending these attributes in Postman

Headers
Content-Type: application/json

Body
{
    "Header": {
        "SystemId": "AW1371",
        "MessageId": "1234567890120006",
        "UserName": "autWakanda",
        "Destination": {
            "Name": null,
            "NameSpace": null,
            "Operation": null
        }
    },
    "CuentaOrigen": {
    "NumeroDocumentoCuentaOrigen": 8232166,
    "TipoDocumentoCuentaOrigen": "1",
    "TipoCuentaDepositoOrigen": "7",
    "NumeroCuentaDepositoOrigen": "40673760005",
    "EntidadCuentaOrigen": "00007",
    "TipoCuentaOrigen": "7",
    "NumeroCuentaOrigen": "40673760005",
    "CodigoFondoCuentaOrigen": "123"
  },
  "CuentaDestino": {
    "TipoDocumentoCuentaDestino": "1",
    "NumeroDocumentoCuentaDestino": 1360740,
    "NumeroFondoInversionCuentaDestino": "0021008106434090",
    "EntidadCuentaDestino": "00532",
    "CodigoFondoCuentaDestino": "21"
  },
  "FormaDePago": "72",
  "ValorAdicion": 133000.31,
  "Oficina": 3132,
  "Canal": "SVE"
}

I tried to set the first character in lowercase but it doesn't work.

This is the exception raised:

Caused by: java.lang.NullPointerException: Cannot invoke "co.com.bancolombia.model.requestheader.RequestHeader.getSystemId()" because the return value of "co.com.bancolombia.api.models.RequestAdicion.getHeader()" is null

Thank you all in advance.

EDIT: I solved the problem setting the annotation @JsonProperty to each field, and creating to each model a NoArgsConstructor initializing variables with no value and the annotation @AllArgsConstructor in the class.