我正在尝试使用Gson将以下POJO序列化为JSON:

public class Member {

    private long id;
    private long customerAccountNumber;
    private long memberNumber;

    private String title;
    private String initials;
    private String telephoneNumber;
    private String maritalStatus;

    private String firstName;
    private String surname;
    private Date birthDate;
    private Date joinDate;
    private String gender;
    private String language;
    private String idNumber;
    private String passportNumber;
    private String mobileNumber;
    private String emailAddress;
    private String fingerprintMinutia;
    private String status;
    private String pinNumber;
    private String commsConsent;
    private String homeTelNumber;
    private String workTelNumber;
    private String faxNumber;
    private String otherTelNumber;

    private Address address;
    private BankAccount bankAccount;
    private Product product;
    private Society society;
    private ArrayList<Beneficiary> beneficiaries;
    private ArrayList<Benefit> benefits;



    public String getCommsConsent() {
        return commsConsent;
    }
    public void setCommsConsent(String commsConsent) {
        this.commsConsent = commsConsent;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public String getInitials() {
        return initials;
    }
    public void setInitials(String initials) {
        this.initials = initials;
    }
    public String getTelephoneNumber() {
        return telephoneNumber;
    }
    public void setTelephoneNumber(String telephoneNumber) {
        this.telephoneNumber = telephoneNumber;
    }
    public String getMaritalStatus() {
        return maritalStatus;
    }
    public void setMaritalStatus(String maritalStatus) {
        this.maritalStatus = maritalStatus;
    }
    public String getPinNumber() {
        return pinNumber;
    }
    public void setPinNumber(String pinNumber) {
        this.pinNumber = pinNumber;
    }
    public ArrayList<Benefit> getBenefits() {
        return benefits;
    }
    public void setBenefits(ArrayList<Benefit> benefits) {
        this.benefits = benefits;
    }
    public ArrayList<Beneficiary> getBeneficiaries() {
        return beneficiaries;
    }
    public void setBeneficiaries(ArrayList<Beneficiary> beneficiaries) {
        this.beneficiaries = beneficiaries;
    }
    public Address getAddress() {
        return address;
    }
    public void setAddress(Address address) {
        this.address = address;
    }
    public BankAccount getBankAccount() {
        return bankAccount;
    }
    public void setBankAccount(BankAccount bankAccount) {
        this.bankAccount = bankAccount;
    }
    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public long getCustomerAccountNumber() {
        return customerAccountNumber;
    }
    public void setCustomerAccountNumber(long customerAccountNumber) {
        this.customerAccountNumber = customerAccountNumber;
    }
    public long getMemberNumber() {
        return memberNumber;
    }
    public void setMemberNumber(long memberNumber) {
        this.memberNumber = memberNumber;
    }
    public String getEmailAddress() {
        return emailAddress;
    }
    public void setEmailAddress(String emailAddress) {
        this.emailAddress = emailAddress;
    }
    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
    public String getSurname() {
        return surname;
    }
    public void setSurname(String surname) {
        this.surname = surname;
    }
    public Date getBirthDate() {
        return birthDate;
    }
    public void setBirthDate(Date birthDate) {
        this.birthDate = birthDate;
    }
    public Date getJoinDate() {
        return joinDate;
    }
    public void setJoinDate(Date joinDate) {
        this.joinDate = joinDate;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public String getIdNumber() {
        return idNumber;
    }
    public void setIdNumber(String idNumber) {
        this.idNumber = idNumber;
    }
    public String getPassportNumber() {
        return passportNumber;
    }
    public void setPassportNumber(String passportNumber) {
        this.passportNumber = passportNumber;
    }
    public String getMobileNumber() {
        return mobileNumber;
    }
    public void setMobileNumber(String mobileNumber) {
        this.mobileNumber = mobileNumber;
    }
    public String getFingerprintMinutia() {
        return fingerprintMinutia;
    }
    public void setFingerprintMinutia(String fingerprintMinutia) {
        this.fingerprintMinutia = fingerprintMinutia;
    }
    public String getStatus() {
        return status;
    }
    public void setStatus(String status) {
        this.status = status;
    }
    public String getLanguage() {
        return language;
    }
    public void setLanguage(String language) {
        this.language = language;
    }
    public Product getProduct() {
        return product;
    }
    public void setProduct(Product product) {
        this.product = product;
    }
    public Society getSociety() {
        return society;
    }
    public void setSociety(Society society) {
        this.society = society;
    }
    public String getHomeTelNumber() {
        return homeTelNumber;
    }
    public void setHomeTelNumber(String homeTelNumber) {
        this.homeTelNumber = homeTelNumber;
    }
    public String getWorkTelNumber() {
        return workTelNumber;
    }
    public void setWorkTelNumber(String workTelNumber) {
        this.workTelNumber = workTelNumber;
    }
    public String getFaxNumber() {
        return faxNumber;
    }
    public void setFaxNumber(String faxNumber) {
        this.faxNumber = faxNumber;
    }
    public String getOtherTelNumber() {
        return otherTelNumber;
    }
    public void setOtherTelNumber(String otherTelNumber) {
        this.otherTelNumber = otherTelNumber;
    }

}

但是，我得到以下错误：

java.lang.IllegalArgument异常：类com.companyname.mobile.dto.受益人声明多个名为好处的JSON字段

受益人类如下所示：

public class Beneficiary extends Member {

    private String type;
    private Date terminationDate;
    private ArrayList<Benefit> benefits;


    public String getType() {
        return type;
    }
    public void setType(String type) {
        this.type = type;
    }
    public Date getTerminationDate() {
        return terminationDate;
    }
    public void setTerminationDate(Date terminationDate) {
        this.terminationDate = terminationDate;
    }
    public ArrayList<Benefit> getBenefits() {
        return benefits;
    }
    public void setBenefits(ArrayList<Benefit> benefits) {
        this.benefits = benefits;
    }

}

有没有办法克服这个问题？我原以为Gson会简单地获取类的数组和ArrayList属性，然后将其转换为JSON数组，例如。

{
    'benefits' : [
        'benefit1' : {...},
        'benefit2' : {...},
        'benefit3' : {...},
    ]
}

提前感谢您的帮助和建议！