code: public InputStream makeRequest(final BackendCaller<? super E, ? super T> backendCaller) throws HodErrorException {
          checkTokenProxyService();
          return makeRequest(tokenProxyService.getTokenProxy(), backendCaller);
      }
docs: Makes a request to HP Haven OnDemand using a TokenProxy provided by a {@link TokenProxyService}, returning the
  response body as an input stream.
  @param backendCaller Makes the request to HP Haven OnDemand
  @return The response body
  @throws HodErrorException
  @throws NullPointerException If a TokenProxyService has not been configured