/**
   * Returns a list of the invoices contained within FreeAgent for the authorised account.
   *
   * @param nestInvoiceItems Should the invoice items also be included with the invoice
   * @return A list of FreeAgentInvoice instances.
   */
  public List<FreeAgentInvoice> getInvoices(boolean nestInvoiceItems) {
    FreeAgentInvoiceWrapper invoicesWrapper =
        freeAgentServiceInstance.getInvoices(nestInvoiceItems);

    if (invoicesWrapper != null && invoicesWrapper.hasInvoices()) {
      return invoicesWrapper.getInvoices();
    } else {
      return null;
    }
  }