code: public SignatureRequest sendTemplateSignatureRequest(TemplateSignatureRequest req) throws HelloSignException {
          return new SignatureRequest(httpClient.withAuth(auth).withPostFields(req.getPostFields())
                  .post(BASE_URI + TEMPLATE_SIGNATURE_REQUEST_URI).asJson());
      }
docs: Creates a new Signature Request based on the template provided.
  
  @param req TemplateSignatureRequest
  @return SignatureRequest
  @throws HelloSignException thrown if there's a problem processing the
  HTTP request or the JSON response.