message: billing - code simplified
diff: @@ -27,12 +27,10 @@ export default class StripeBillingIntegration extends BillingIntegration<StripeB
  private static readonly STRIPE_MAX_LIST = 100;
  private axiosInstance: AxiosInstance;
  private stripe: Stripe;
  - private stripeSettings: StripeBillingSetting;
  constructor(tenantId: string, settings: StripeBillingSetting) {
  super(tenantId, settings);
  this.axiosInstance = AxiosFactory.getAxiosInstance(this.tenantID);
  - this.stripeSettings = settings;
  }
  public async getStripeInstance(): Promise<Stripe> {
  @@ -45,8 +43,7 @@ export default class StripeBillingIntegration extends BillingIntegration<StripeB
  // Initialize Stripe
  if (!this.stripe) {
  // STRIPE not yet initialized - let's do it!
  - this.settings.currency = this.stripeSettings.currency;
  - this.settings.secretKey = await Cypher.decrypt(this.tenantID, this.stripeSettings.secretKey);
  + this.settings.secretKey = await Cypher.decrypt(this.tenantID, this.settings.secretKey);
  // Check Key
  if (!this.settings.secretKey) {
  throw new BackendError({
  @@ -630,7 +627,7 @@ export default class StripeBillingIntegration extends BillingIntegration<StripeB
  }
  } else {
  // We already have a draft invoice - let's add an item to it
  - newInvoiceItem = await this.createInvoiceItem(billingUser, draftInvoice.invoiceID, lineItemInputParameters, transaction.id);
  + newInvoiceItem = await this.createInvoiceItem(billingUser, draftInvoice.invoiceID, lineItemInputParameters, this.buildIdemPotencyKey(transaction));
  if (!newInvoiceItem) {
  throw new BackendError({
  message: 'Failed to create a new item',
  