title: mastercard hosted session integration issue
body: <p>I want to integrate payment in my website using mastercard payment gateway system.  I use the hosted session method for the integration. I follow the <a href="https://network.gateway.mastercard.com/api/documentation/integrationGuidelines/hostedSession/integrationModelHostedSession.html?locale=en_US#x_paymentTypesHS" rel="noreferrer">mastercard hosted session</a></p>
  
  <p>My javascript code is</p>
  
  <pre><code>&lt;script src="https://network.gateway.mastercard.com/form/version/51/merchant/
  **&lt;testmerchantID&gt;**/session.js"&gt;&lt;/script&gt;
  &lt;script&gt;
      if (self === top) {
      var antiClickjack = document.getElementById("antiClickjack");
      antiClickjack.parentNode.removeChild(antiClickjack);
  } else {
      top.location = self.location;
  }
  
  PaymentSession.configure({
      fields: {
          // ATTACH HOSTED FIELDS TO YOUR PAYMENT PAGE FOR A CREDIT CARD
          card: {
              number: "#card-number",
              securityCode: "#security-code",
              expiryMonth: "#expiry-month",
              expiryYear: "#expiry-year"
          }
      },
      session: 'abc456',
      //SPECIFY YOUR MITIGATION OPTION HERE
      frameEmbeddingMitigation: ["javascript"],
      callbacks: {
          initialized: function(response) {
              //console.log(response.status); 
          },
          formSessionUpdate: function(response) {
              // HANDLE RESPONSE FOR UPDATE SESSION
              if (response.status) {
                  if ("ok" == response.status) {
                      console.log("Session updated with data: " + response.session.id);
  
                      //check if the security code was provided by the user
                      if (response.sourceOfFunds.provided.card.securityCode) {
                          console.log("Security code was provided.");
                      }
  
                      //check if the user entered a Mastercard credit card
                      if (response.sourceOfFunds.provided.card.scheme == 'MASTERCARD') {
                          console.log("The user entered a Mastercard credit card.")
                      }
                  } else if ("fields_in_error" == response.status)  {
  
                      console.log("Session update failed with field errors.");
                      if (response.errors.cardNumber) {
                          console.log("Card number invalid or missing.");
                      }
                      if (response.errors.expiryYear) {
                          console.log("Expiry year invalid or missing.");
                      }
                      if (response.errors.expiryMonth) {
                          console.log("Expiry month invalid or missing.");
                      }
                      if (response.errors.securityCode) {
                          console.log("Security code invalid.");
                      }
                  } else if ("request_timeout" == response.status)  {
                      console.log("Session update failed with request timeout: " + response.errors.message);
                  } else if ("system_error" == response.status)  {
                      console.log("Session update failed with system error: " + response.errors.message);
                  }
              } else {
                  console.log("Session update failed: " + response);
              }
          }
      },
      interaction: {
          displayControl: {
              formatCard: "EMBOSSED",
              invalidFieldCharacters: "REJECT"
          }
      },
      order: {
          amount: 10.00,
          currency: "AED" ,
          id:123
      }
    });
  
  function pay() {
      // UPDATE THE SESSION WITH THE INPUT FROM HOSTED FIELDS
      PaymentSession.updateSessionFromForm('card');
  }
  &lt;/script&gt;
  </code></pre>
  
  <p>I have used option <strong>session:'dummy data'</strong> inside configuration option since I need to identify each transaction. It gives me an error</p>
  
  <pre><code>Session update failed with system error: Form Session not found or expired.
  </code></pre>
  
  <p>When I comment these line, I am getting sessionID genereated by the library in the response. I am confused how to identify each transaction.Please help me</p>