Firebase：在类中找不到可序列化的属性。

我正在创建 Firebase 数据库时遇到了阻碍。

我试图建立一个非常简单的类：

package com.glups.model;
import com.google.firebase.database.IgnoreExtraProperties;
@IgnoreExtraProperties
public class AlumnoFB {
    private String nombre;
    private String apellidos;
    private String telefono;
    private String email;
    private Boolean tieneWhatsapp;
    private Boolean tieneTelegram;
    private Boolean tieneHangouts;
    private Long formaPago;
    private Double ratioHora;
    private Double precioHora;
    private Double horasCompensadas;
    public AlumnoFB() {
        // Default constructor required for calls to DataSnapshot.getValue(User.class)
    }
    public AlumnoFB(String nombre,
                    String apellidos,
                    String telefono,
                    String email,
                    Boolean tieneWhatsapp,
                    Boolean tieneTelegram,
                    Boolean tieneHangouts,
                    Long formaPago,
                    Double ratioHora,
                    Double precioHora,
                    Double horasCompensadas) {
        this.nombre = nombre;
        this.apellidos = apellidos;
        this.telefono = telefono;
        this.email = email;
        this.tieneWhatsapp = tieneWhatsapp;
        this.tieneTelegram = tieneTelegram;
        this.tieneHangouts = tieneHangouts;
        this.formaPago = formaPago;
        this.ratioHora = ratioHora;
        this.precioHora = precioHora;
        this.horasCompensadas = horasCompensadas;
    }
}

它几乎就像 Firebase 的一个示例类。

从 getUser() 获取到的应用程序用户已登录 Firebase。

当我调用 SetValue 时：

AlumnoFB alumno = new AlumnoFB("", "", "", "", false, false, false, ((Integer)FormaPago.INT_NO_PAGADO).longValue(), 0.0, 0.0, 0.0);
    mDatabase.child("AlumnoFB").child(ControlClasesFirebase.getUser().getUid()).setValue(alumno) ;

就会出现致命异常。

06-10 10:17:37.179 13841-13841/com.glups.controlclases E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.glups.controlclases, PID: 13841 com.google.firebase.database.DatabaseException: No properties to serialize found on class com.glups.model.AlumnoFB
at com.google.android.gms.internal.zzaix$zza.(Unknown Source)
at com.google.android.gms.internal.zzaix.zzj(Unknown Source)
at com.google.android.gms.internal.zzaix.zzaw(Unknown Source)
at com.google.android.gms.internal.zzaix.zzav(Unknown Source)
at com.google.firebase.database.DatabaseReference.zza(Unknown Source)
at com.google.firebase.database.DatabaseReference.setValue(Unknown Source)
at com.glups.controlclases.MainActivity$4.onClick(MainActivity.java:305)
at android.view.View.performClick(View.java:4780)
at android.view.View$PerformClick.run(View.java:19866)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5258)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

我检查了所有类型，所有类型都被接受。问题出在哪里？