Don't modify globalConf while creating client.

Author: milindl

lib/client.js

@@ -52,11 +52,18 @@ function Client(globalConf, SubClientType, topicConf) {
   // key is a real conf value
   delete globalConf.event_cb;
 
+  // These properties are not meant to be user-set.
+  // Clients derived from this might want to change them, but for
+  // now we override them.
   globalConf['client.software.name'] = 'confluent-kafka-javascript';
   globalConf['client.software.version'] = `${bindingVersion}-librdkafka-${Kafka.librdkafkaVersion}`;
 
   this._client = new SubClientType(globalConf, topicConf);
 
+  // We should not modify the globalConf object. We have cloned it already.
+  delete globalConf['client.software.name'];
+  delete globalConf['client.software.version'];
+
   var extractFunctions = function(obj) {
     obj = obj || {};
     var obj2 = {};