改进API Post调用返回错误500，与邮递员工作良好

Question

public class SignUpCreds {
@SerializedName("username")
@Expose
private String username;
@SerializedName("email")
@Expose
private String email;
@SerializedName("password")
@Expose
private String password;


public SignUpCreds(String username, String email, String password) {
    this.username = username;
    this.email = email;
    this.password = password;
}

public class SignUpResponce {
@SerializedName("id")
@Expose
private Integer id;
@SerializedName("username")
@Expose
private String username;
@SerializedName("email")
@Expose
private String email;
@SerializedName("password")
@Expose
private String password;
@SerializedName("dateRegistered")
@Expose
private Integer dateRegistered;

public Integer getId() {
    return id;
}

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

public String getUsername() {
    return username;
}

public void setUsername(String username) {
    this.username = username;
}

public String getEmail() {
    return email;
}

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

public String getPassword() {
    return password;
}

public void setPassword(String password) {
    this.password = password;
}

public Integer getDateRegistered() {
    return dateRegistered;
}

public void setDateRegistered(Integer dateRegistered) {
    this.dateRegistered = dateRegistered;
}

{
"username": "doe2jane",
"email": "[e-mail]",
"password": "janedoe"

{
"id": 7,
"username": "doe2jane",
"email": "[e-mail]",
"password": "janedoe",
"dateRegistered": 1499870604166

我的签名

SignUpCreds creds=新的SignUpCreds（用户名、电子邮件、密码）；

改装类别：

public class AuthUtil {
private static Retrofit sRetrofit = null;

public static Retrofit getRetrofit(String url){
    Gson gson = new GsonBuilder()
            .setLenient()
            .create();
    if (sRetrofit == null){
        sRetrofit  = new Retrofit.Builder()
                .baseUrl(url)
                .addConverterFactory(GsonConverterFactory.create(gson))
                .build();
    }
    return sRetrofit;
}