Confluent client unexpectedly mutates function arguments

[justjake]

The KafkaJS consumer unexpected mutates the inputs to some of its methods. For example, kafkaJSClient.pause(topics) will mutate the input topics by adding the .partitions key if it's undefined. I generally expect that Javascript functions treat their inputs as immutable, so I don't need to defensively clone function arguments before passing them to a library. Mutation can lead to unexpected results.

In this case, I want to call .pause(assignments) during the rebalance callback for some assignments. This is mutating the assignment objects, leading to unexpected side effects in the assignment logic.

[milindl]

Yes, that's right, I'll change this and check other functions, too, we shouldn't be mutating arguments.

[milindl]

Closing with release 0.1.17-devel