code: public EmbeddedResponse getEmbeddedSignUrl(String signatureId) throws HelloSignException {
          String url = BASE_URI + EMBEDDED_SIGN_URL_URI + "/" + signatureId;
          return new EmbeddedResponse(httpClient.withAuth(auth).post(url).asJson());
      }
docs: Retrieves the necessary information to build an embedded signature
  request.
  
  @param signatureId String ID of the signature request to embed
  @return EmbeddedResponse
  @throws HelloSignException thrown if there's a problem processing the
  HTTP request or the JSON response.