Bugfix: Issue 3111 (prebid#3122)

* bug fix for Prebid issue 3111

* adding try-catch around the fix

* added a warning on exception handling

* updated the message

* using util.deepClone

* changed variable name from original_bid to originalBid

* unit test case for checking original object modification

modules/pubmaticBidAdapter.js

@@ -319,7 +319,9 @@ export const spec = {
     var dctr = '';
     var dctrLen;
     var dctrArr = [];
-    validBidRequests.forEach(bid => {
+    var bid;
+    validBidRequests.forEach(originalBid => {
+      bid = utils.deepClone(originalBid);
       _parseAdSlot(bid);
       if (bid.params.hasOwnProperty('video')) {
         if (!(bid.params.adSlot && bid.params.adUnit && bid.params.adUnitIndex)) {

test/spec/modules/pubmaticBidAdapter_spec.js

@@ -217,7 +217,13 @@ describe('PubMatic adapter', function () {
     });
 
   	describe('Request formation', function () {
-  		it('Endpoint checking', function () {
+  		it('buildRequests function should not modify original bidRequests object', function () {
+        let originalBidRequests = utils.deepClone(bidRequests);
+        let request = spec.buildRequests(bidRequests);
+        expect(bidRequests).to.deep.equal(originalBidRequests);
+      });
+
+      it('Endpoint checking', function () {
   		  let request = spec.buildRequests(bidRequests);
         expect(request.url).to.equal('//hbopenbid.pubmatic.com/translator?source=prebid-client');
         expect(request.method).to.equal('POST');