code: public BillingPlanUpdateResponse updatePlan(String accountId, BillingPlanInformation billingPlanInformation) throws ApiException {
      return updatePlan(accountId, billingPlanInformation, null);
    }
docs: Updates the account billing plan.
  Updates the billing plan information, billing address, and credit card information for the specified account.
  @param accountId The external account number (int) or account ID Guid. (required)
  @param billingPlanInformation  (optional)
  @return BillingPlanUpdateResponse