retrofit 2 post - getting internal server error (500) - retrofit

Question

I'm trying to use retrofit2 with Koltin in Android Studio as part of jetpack compose application. I'm sending a POST and keep getting error 500. I don't have access to the server code so I'm trying to figure out what am I doing wrong.
This is the interface I have declared for building the retrofit object:
I tried three different ways of declaring the POST endpoint.
#Singleton
interface IsrPayService {
#Headers ("Content-Type: application/json")
#POST("v3/driver/new-credit-driver")
suspend fun signUp(#Body user: UserDriver): Call\<WsError?\>
#Headers (
"Content-Type: application/json",
"Accept: application/json")
#POST("v3/driver/new-credit-driver")
suspend fun signup2(#Body user: UserDriver): retrofit2.Response<WsError>
#FormUrlEncoded
#POST("v3/driver/new-credit-driver")
suspend fun signupUrlEncoded(
#Field("firstName") firstName: String,
#Field("lastName") lastName: String): retrofit2.Response<WsError>
}
The data I am trying to send is UserDriver and I declared all the internal data classes below:
data class UserDriver(
#SerializedName("firstName") val firstName: String = "default",
#SerializedName("lastName") val lastName: String = "default",
#SerializedName("civilId") val civilId: String = "default",
#SerializedName("vehicleLicensingNumber") val vehicleLicensingNumber: String = "default",
#SerializedName("vehicleManufacturer") val vehicleManufacturer: String = "default",
#SerializedName("vehicleModel") val vehicleModel: String = "default",
#SerializedName("vehicleManufactureYear") val vehicleManufactureYear: String = "1973",
#SerializedName("counterModel") val counterModel: String = "default",
#SerializedName("authorizedEmployerNumber") val authorizedEmployerNumber: String = "default",
#SerializedName("bankAccountId") val bankAccountId: String = "default",
#SerializedName("bankAccountBranch") val bankAccountBranch: Int = 0,
#SerializedName("bankId") val bankId:Int = 123456,
#SerializedName("email") val email: String = "default",
#SerializedName("dob") val dob: DateIndicator = DateIndicator(date = 3, month = 4, year = 2023),
#SerializedName("address") val address: Address = Address (Coordinates(0,0),"מודיעין","טשרניחובסקי","12"),
#SerializedName("phoneNumber") val phoneNumber: String = "default",
#SerializedName("driverLicenseId") val driverLicenseId: Int = 0,
#SerializedName("civilIdPhoto") val civilIdPhoto: String = "default",
#SerializedName("driverLicensePhoto") val driverLicensePhoto: String = "default",
#SerializedName("signaturePhoto") val signaturePhoto: String = "default"
)
data class DateIndicator(
#SerializedName("date")
#Expose
val date: Int,
#SerializedName("month")
#Expose
val month: Int,
#SerializedName("year")
#Expose
val year: Int
)
I think #Expose is not required but tried it just in case..
data class Address (
#SerializedName("coordinates")
#Expose
val coordinates: Coordinates,
#SerializedName("city")
#Expose
val city: String,
#SerializedName("street")
#Expose
val street: String,
#SerializedName("number")
#Expose
val number: String
)
data class Coordinates (
#SerializedName("latitude")
#Expose
val latitude: Int,
#SerializedName("longitude")
#Expose
val longitude: Int
)
I tried to methods of getting the response:
suspend fun driverSignUp(user: UserDriver, onResult: (WsError?) -> Unit) {
try {
ws.signUp(user = user). enqueue (
object: Callback<WsError?> {
override fun onResponse(call: Call<WsError?>, response: Response<WsError?>) {
Log.d("driverSignUp",
"onResponse: response.isSuccessful = ${response.isSuccessful}")
var wsError: WsError? = null
wsError = if(!response.isSuccessful){
WsError(
body = "",
isError = true,
error = yz.learning.isrpaytest.model.Error(
errorCode = response.code(),
errorMessage = ErrorMessage(
enUs = response.message(),
heIl = response.message())))
} else {
response.body()
}
onResult(wsError)
}
override fun onFailure(call: Call<WsError?>, t: Throwable) {
Log.d("driverSignUp", "onFailure: ")
onResult(null)
}
}
)
} catch (exception: Exception) {
Log.d("driverSignUp", "driverSignUp exception: ${exception.message}")
onResult(
WsError(
body = "",
isError = true,
error = yz.learning.isrpaytest.model.Error(
errorCode = 0,
errorMessage = ErrorMessage(
enUs = exception.message!!,
heIl = exception.message!!)))
)
}
}
suspend fun driverSignUp2(user: UserDriver): retrofit2.Response<WsError>{
return ws.signup2(user)
}
I don't understand why I keep getting Internal server error. I have a feeling I have to send the data as a JSON string and not as an Object but as far as I understand this is supposed to be automatically using the gson converter, no?
I can try a simpler endpoint, but I think I will end up with the same problem.
I will appreciate any help since I'm stuck with this issue for a couple of days.
Thanks,
Yariv