diff --git a/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kBankingClient.kt b/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kBankingClient.kt
index a6a29432..bedb8f91 100644
--- a/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kBankingClient.kt
+++ b/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kBankingClient.kt
@@ -17,9 +17,9 @@ open class FinTs4kBankingClient(
     constructor(callback: BankingClientCallback) : this(FinTsClientConfiguration(), callback)
 
 
-    private val mapper = FinTs4kMapper()
+    protected val mapper = FinTs4kMapper()
 
-    private val client = FinTsClient(config, BridgeFintTsToBankingClientCallback(callback, mapper))
+    protected val client = FinTsClient(config, BridgeFintTsToBankingClientCallback(callback, mapper))
 
 
     override suspend fun getAccountDataAsync(request: GetAccountDataRequest): Response<GetAccountDataResponse> {
diff --git a/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kMapper.kt b/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kMapper.kt
index 58995c4a..5027a311 100644
--- a/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kMapper.kt
+++ b/FinTs4jBankingClient/src/commonMain/kotlin/net/codinux/banking/client/fints4k/FinTs4kMapper.kt
@@ -22,10 +22,10 @@ import kotlin.io.encoding.ExperimentalEncodingApi
 
 open class FinTs4kMapper {
 
-    private val fintsModelMapper = FinTsModelMapper()
+    protected val fintsModelMapper = FinTsModelMapper()
 
 
-    fun mapToGetAccountDataParameter(credentials: AccountCredentials, options: GetAccountDataOptions) = GetAccountDataParameter(
+    open fun mapToGetAccountDataParameter(credentials: AccountCredentials, options: GetAccountDataOptions) = GetAccountDataParameter(
         credentials.bankCode, credentials.loginName, credentials.password,
         options.accounts.map { BankAccountIdentifierImpl(it.identifier, it.subAccountNumber, it.iban) },
         options.retrieveBalance,
@@ -34,7 +34,7 @@ open class FinTs4kMapper {
     )
 
 
-    fun map(response: net.dankito.banking.client.model.response.GetAccountDataResponse): Response<GetAccountDataResponse> {
+    open fun map(response: net.dankito.banking.client.model.response.GetAccountDataResponse): Response<GetAccountDataResponse> {
         return if (response.successful && response.customerAccount != null) {
             Response.success(GetAccountDataResponse(mapCustomer(response.customerAccount!!)))
         } else {
@@ -43,25 +43,25 @@ open class FinTs4kMapper {
     }
 
 
-    fun mapToCustomerAccountViewInfo(bank: BankData): CustomerAccountViewInfo = CustomerAccountViewInfo(
+    open fun mapToCustomerAccountViewInfo(bank: BankData): CustomerAccountViewInfo = CustomerAccountViewInfo(
         bank.bankCode, bank.customerId, bank.bankName
     )
 
-    fun mapToBankAccountViewInfo(account: AccountData): BankAccountViewInfo = BankAccountViewInfo(
+    open 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(
+    protected open 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) }
     )
 
 
-    private fun mapAccount(account: net.dankito.banking.client.model.BankAccount): BankAccount = BankAccount(
+    protected open fun mapAccount(account: net.dankito.banking.client.model.BankAccount): BankAccount = BankAccount(
         account.identifier, account.accountHolderName, mapAccountType(account.type), account.iban, account.subAccountNumber,
         account.productName, account.currency, account.accountLimit, account.isAccountTypeSupportedByApplication,
         mapFeatures(account),
@@ -71,10 +71,10 @@ open class FinTs4kMapper {
         bookedTransactions = account.bookedTransactions.map { mapTransaction(it) }.toMutableList()
     )
 
-    private fun mapAccountType(type: net.dankito.banking.client.model.BankAccountType): BankAccountType =
+    protected open fun mapAccountType(type: net.dankito.banking.client.model.BankAccountType): BankAccountType =
         BankAccountType.valueOf(type.name)
 
-    private fun mapFeatures(account: net.dankito.banking.client.model.BankAccount): Set<BankAccountFeatures> = buildSet {
+    protected open fun mapFeatures(account: net.dankito.banking.client.model.BankAccount): Set<BankAccountFeatures> = buildSet {
         if (account.supportsRetrievingBalance) {
             add(BankAccountFeatures.RetrieveBalance)
         }
@@ -90,7 +90,7 @@ open class FinTs4kMapper {
     }
 
 
-    private fun mapTransaction(transaction: net.dankito.banking.client.model.AccountTransaction): AccountTransaction = AccountTransaction(
+    protected open fun mapTransaction(transaction: net.dankito.banking.client.model.AccountTransaction): AccountTransaction = AccountTransaction(
         mapAmount(transaction.amount), transaction.amount.currency.code, transaction.unparsedReference,
         transaction.bookingDate, transaction.valueDate,
         transaction.otherPartyName, transaction.otherPartyBankCode, transaction.otherPartyAccountId,
@@ -100,12 +100,12 @@ open class FinTs4kMapper {
         // TODO: map other properties
     )
 
-    private fun mapNullableAmount(amount: Money?) = amount?.let { mapAmount(it) }
+    protected open fun mapNullableAmount(amount: Money?) = amount?.let { mapAmount(it) }
 
-    private fun mapAmount(amount: Money) = Amount.fromString(amount.amount.string.replace(',', '.'))
+    protected open fun mapAmount(amount: Money) = Amount.fromString(amount.amount.string.replace(',', '.'))
 
 
-    fun mapTanChallenge(challenge: net.codinux.banking.fints.model.TanChallenge): TanChallenge {
+    open fun mapTanChallenge(challenge: net.codinux.banking.fints.model.TanChallenge): TanChallenge {
         val type = mapTanChallengeType(challenge)
         val action = mapActionRequiringTan(challenge.forAction)
         val tanMethod = mapTanMethod(challenge.tanMethod)
@@ -118,38 +118,38 @@ open class FinTs4kMapper {
         return TanChallenge(type, action, challenge.messageToShowToUser, tanMethod, tanImage, flickerCode, customer, account)
     }
 
-    private fun mapTanChallengeType(challenge: net.codinux.banking.fints.model.TanChallenge): TanChallengeType = when {
+    protected open fun mapTanChallengeType(challenge: net.codinux.banking.fints.model.TanChallenge): TanChallengeType = when {
         challenge is ImageTanChallenge -> TanChallengeType.Image
         challenge is FlickerCodeTanChallenge -> TanChallengeType.Flickercode
         else -> TanChallengeType.EnterTan
     }
 
-    private fun mapActionRequiringTan(action: net.codinux.banking.fints.model.ActionRequiringTan): ActionRequiringTan =
+    protected open fun mapActionRequiringTan(action: net.codinux.banking.fints.model.ActionRequiringTan): ActionRequiringTan =
         ActionRequiringTan.valueOf(action.name)
 
-    private fun mapTanMethod(method: net.codinux.banking.fints.model.TanMethod): TanMethod = TanMethod(
+    protected open fun mapTanMethod(method: net.codinux.banking.fints.model.TanMethod): TanMethod = TanMethod(
         method.displayName, mapTanMethodType(method.type), method.securityFunction.code, method.maxTanInputLength, mapAllowedTanFormat(method.allowedTanFormat)
     )
 
-    private fun mapTanMethodType(type: net.codinux.banking.fints.model.TanMethodType): TanMethodType =
+    protected open fun mapTanMethodType(type: net.codinux.banking.fints.model.TanMethodType): TanMethodType =
         TanMethodType.valueOf(type.name)
 
-    private fun mapAllowedTanFormat(allowedTanFormat: net.codinux.banking.fints.messages.datenelemente.implementierte.tan.AllowedTanFormat?): AllowedTanFormat =
+    protected open fun mapAllowedTanFormat(allowedTanFormat: net.codinux.banking.fints.messages.datenelemente.implementierte.tan.AllowedTanFormat?): AllowedTanFormat =
         allowedTanFormat?.let { AllowedTanFormat.valueOf(it.name) } ?: AllowedTanFormat.Alphanumeric
 
-    private fun mapTanImage(image: net.codinux.banking.fints.tan.TanImage): TanImage =
+    protected open fun mapTanImage(image: net.codinux.banking.fints.tan.TanImage): TanImage =
         TanImage(image.mimeType, mapToBase64(image.imageBytes), mapException(image.decodingError))
 
     @OptIn(ExperimentalEncodingApi::class)
-    private fun mapToBase64(bytes: ByteArray): String {
+    protected open fun mapToBase64(bytes: ByteArray): String {
         return Base64.Default.encode(bytes)
     }
 
-    private fun mapFlickerCode(flickerCode: net.codinux.banking.fints.tan.FlickerCode): FlickerCode =
+    protected open fun mapFlickerCode(flickerCode: net.codinux.banking.fints.tan.FlickerCode): FlickerCode =
         FlickerCode(flickerCode.challengeHHD_UC, flickerCode.parsedDataSet, mapException(flickerCode.decodingError))
 
 
-    private fun <T> mapError(response: net.dankito.banking.client.model.response.GetAccountDataResponse): Response<T> {
+    protected open fun <T> mapError(response: net.dankito.banking.client.model.response.GetAccountDataResponse): Response<T> {
         return if (response.error != null) {
             Response.error(ErrorType.valueOf(response.error!!.name), if (response.error == ErrorCode.BankReturnedError) null else response.errorMessage,
                 if (response.error == ErrorCode.BankReturnedError && response.errorMessage !== null) listOf(response.errorMessage!!) else emptyList())
@@ -158,7 +158,7 @@ open class FinTs4kMapper {
         }
     }
 
-    private fun mapException(exception: Exception?): String? =
+    protected open fun mapException(exception: Exception?): String? =
         exception?.stackTraceToString()
 
 }
\ No newline at end of file