If you have config A and B and one of them overrides the other one, then the simplest way for you way to find it yourself without any help is to make a mistake in one of configuration and see if it affects your code. If not revert that change and just to be sure change second config. At least one of those changes should fail.
# Hackney -> HackHey
config :tesla, adapter: {Tesla.Adapter.HackHey, recv_timeout: 27_000, pool: false}
You should have an error that a module or it’s function is not available and that the module is not loaded.
I don’t know if it’s worth it … Depends on how you see it … 
- If that’s the only problem and you are able to fix it then I do not see a need to do that other than a bigger code refactor
- If you plan code refactor anyway then why not giving a try other hex dependency?
- Salary you can offer me
More or less seriously, but the general rule is that you should be the only person to make decisions for you. Nobody who only give you “empty advice” would take responsibility for what you do. This applies not only to programming, but any topic around investing (time, money, resources etc.).
Depends on what you ask … Many developers made a code refactor at least once and with good library API it should be enough simple to not even touch tests and the rest of code. If you mean an edge-case with a custom server not supporting any commonly supported HTTP header then I guess that most people may at most heard about such case, but never had a chance to work on it.
The simplest way is to show some example code, but I guess that may take some time for some cases. You can always ask somebody for help and invite him to project. As a senior Elixir developer I’m helping with creating issues and pull requests in last 7 years:
Recently in May I have even done a major code refactor for a public repository:
Here is my GitHub profile:
