Only adding the basic CustomerAccount and BankAccount data to TanChallenge. It's absolutely not senseful to send the whole CustomerAccount and BankAccount object over the wire in JSON body

BankingClientModel/src/commonMain/kotlin/net/codinux/banking/client/model/BankAccount.kt

@@ -7,7 +7,7 @@ import net.codinux.banking.client.model.config.NoArgConstructor
 open class BankAccount(
     val identifier: String,
     var accountHolderName: String,
-    val type: BankAccountType = BankAccountType.CheckingAccount,
+    val type: BankAccountType = BankAccountType.Other,
     val iban: String? = null,
     val subAccountNumber: String? = null,
     val productName: String? = null,

BankingClientModel/src/commonMain/kotlin/net/codinux/banking/client/model/BankAccountViewInfo.kt

@@ -0,0 +1,18 @@
+package net.codinux.banking.client.model
+
+import net.codinux.banking.client.model.config.NoArgConstructor
+
+/**
+ * Contains only the basic info of a [BankAccount], just enough that a client application can display it to the user
+ * and the user knows exactly which [BankAccount] is meant / referred.
+ */
+@NoArgConstructor
+open class BankAccountViewInfo(
+    val identifier: String,
+    val subAccountNumber: String? = null,
+    val type: BankAccountType = BankAccountType.Other,
+    val iban: String? = null,
+    val productName: String? = null,
+) {
+    override fun toString() = "$type $productName $identifier"
+}

BankingClientModel/src/commonMain/kotlin/net/codinux/banking/client/model/CustomerAccountViewInfo.kt

@@ -0,0 +1,16 @@
+package net.codinux.banking.client.model
+
+import net.codinux.banking.client.model.config.NoArgConstructor
+
+/**
+ * Contains only the basic info of a [CustomerAccount], just enough that a client application can display it to the user
+ * and the user knows exactly which [CustomerAccount] is meant / referred.
+ */
+@NoArgConstructor
+open class CustomerAccountViewInfo(
+    val bankCode: String,
+    var loginName: String,
+    val bankName: String
+) {
+    override fun toString() = "$bankCode $bankName $loginName"
+}

BankingClientModel/src/commonMain/kotlin/net/codinux/banking/client/model/tan/TanChallenge.kt

@@ -1,7 +1,7 @@
 package net.codinux.banking.client.model.tan
 
-import net.codinux.banking.client.model.BankAccount
-import net.codinux.banking.client.model.CustomerAccount
+import net.codinux.banking.client.model.BankAccountViewInfo
+import net.codinux.banking.client.model.CustomerAccountViewInfo
 import net.codinux.banking.client.model.config.NoArgConstructor
 
 @NoArgConstructor
@@ -12,8 +12,8 @@ open class TanChallenge(
     val tanMethod: TanMethod,
     val tanImage: TanImage? = null,
     val flickerCode: FlickerCode? = null,
-    val customer: CustomerAccount,
-    val account: BankAccount? = null
+    val customer: CustomerAccountViewInfo,
+    val account: BankAccountViewInfo? = null
     // TODO: add availableTanMethods, selectedTanMedium, availableTanMedia
 ) {
 

FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kMapper.kt

@@ -11,6 +11,7 @@ import net.codinux.banking.client.model.tan.TanChallenge
 import net.codinux.banking.client.model.tan.TanImage
 import net.codinux.banking.client.model.tan.TanMethod
 import net.codinux.banking.client.model.tan.TanMethodType
+import net.dankito.banking.client.model.BankAccountIdentifierImpl
 import net.dankito.banking.client.model.parameter.GetAccountDataParameter
 import net.dankito.banking.client.model.parameter.RetrieveTransactions
 import net.dankito.banking.client.model.response.ErrorCode
@@ -26,7 +27,7 @@ open class FinTs4kMapper {
 
     fun mapToGetAccountDataParameter(credentials: AccountCredentials, options: GetAccountDataOptions) = GetAccountDataParameter(
         credentials.bankCode, credentials.loginName, credentials.password,
-        null,
+        options.accounts.map { BankAccountIdentifierImpl(it.identifier, it.subAccountNumber, it.iban) },
         options.retrieveBalance,
         RetrieveTransactions.valueOf(options.retrieveTransactions.name), options.retrieveTransactionsFrom, options.retrieveTransactionsTo,
         abortIfTanIsRequired = options.abortIfTanIsRequired
@@ -42,15 +43,23 @@ open class FinTs4kMapper {
     }
 
 
+    fun mapToCustomerAccountViewInfo(bank: BankData): CustomerAccountViewInfo = CustomerAccountViewInfo(
+        bank.bankCode, bank.customerId, bank.bankName
+    )
+
+    fun mapToBankAccountViewInfo(account: AccountData): BankAccountViewInfo = BankAccountViewInfo(
+        account.accountIdentifier, account.subAccountAttribute,
+        mapAccountType(fintsModelMapper.map(account.accountType)),
+        account.iban, account.productName
+    )
+
+
     private fun mapCustomer(customer: net.dankito.banking.client.model.CustomerAccount): CustomerAccount = CustomerAccount(
         customer.bankCode, customer.loginName, customer.password,
         customer.bankName, customer.bic, customer.customerName, customer.userId,
         customer.accounts.map { mapAccount(it) }
     )
 
-    fun mapCustomer(bank: BankData): CustomerAccount =
-        mapCustomer(fintsModelMapper.map(bank))
-
 
     private fun mapAccount(account: net.dankito.banking.client.model.BankAccount): BankAccount = BankAccount(
         account.identifier, account.accountHolderName, mapAccountType(account.type), account.iban, account.subAccountNumber,
@@ -62,9 +71,6 @@ open class FinTs4kMapper {
         bookedTransactions = account.bookedTransactions.map { mapTransaction(it) }.toMutableList()
     )
 
-    fun mapAccount(account: AccountData): BankAccount =
-        mapAccount(fintsModelMapper.map(account))
-
     private fun mapAccountType(type: net.dankito.banking.client.model.BankAccountType): BankAccountType =
         BankAccountType.valueOf(type.name)
 
@@ -103,8 +109,8 @@ open class FinTs4kMapper {
         val type = mapTanChallengeType(challenge)
         val action = mapActionRequiringTan(challenge.forAction)
         val tanMethod = mapTanMethod(challenge.tanMethod)
-        val customer = mapCustomer(challenge.bank)
-        val account = challenge.account?.let { mapAccount(it) }
+        val customer = mapToCustomerAccountViewInfo(challenge.bank)
+        val account = challenge.account?.let { mapToBankAccountViewInfo(it) }
 
         val tanImage = if (challenge is ImageTanChallenge) mapTanImage(challenge.image) else null
         val flickerCode = if (challenge is FlickerCodeTanChallenge) mapFlickerCode(challenge.flickerCode) else null