code: public TemplateInformation listTemplates(String accountId, String envelopeId) throws ApiException {
      return listTemplates(accountId, envelopeId, null);
    }
docs: Get List of Templates used in an Envelope
  This returns a list of the server-side templates, their name and ID, used in an envelope.
  @param accountId The external account number (int) or account ID Guid. (required)
  @param envelopeId The envelopeId Guid of the envelope being accessed. (required)
  @return TemplateInformation