code: public OAuthCredentialsResponse new10aTemporaryTokenRequest(String redirectUri)
              throws IOException {
          OAuthGetTemporaryToken temporaryToken =
                  new OAuthGetTemporaryToken(getTemporaryTokenRequestUrl());
          OAuthHmacSigner signer = new OAuthHmacSigner();
          ClientParametersAuthentication clientAuthentication = (ClientParametersAuthentication) getClientAuthentication();
          signer.clientSharedSecret = clientAuthentication.getClientSecret();
          temporaryToken.signer = signer;
          temporaryToken.consumerKey = clientAuthentication.getClientId();
          temporaryToken.callback = redirectUri;
          temporaryToken.transport = getTransport();
          return temporaryToken.execute();
      }
docs: Returns the response of a Request Token request as defined in <a
  href="http://oauth.net/core/1.0a/#auth_step1">Obtaining an Unauthorized
  Request Token</a>.
  
  @param redirectUri the {@code oauth_callback} as defined in <a
  href="http://oauth.net/core/1.0a/#rfc.section.6.1.1">Consumer
  Obtains a Request Token</a>
  @return
  @throws IOException