Default Authorization header no longer working in 0.19.0

Describe the bug Since axios 0.19.0, the default Authorization header is no longer set in query. It works in 0.18.X.

To Reproduce Create an axios adapter and set to it a default Authorization header, nothing is sent in the query.

axios.defaults.headers.common.Authorization = 'Bearer ANY SECURITY TOKEN';

[glebtv]

axios global defaults (axios.defaults.headers) seem to no longer affect prevoiusly-created axios client instances. Is this an intended change?

Example: 0.18 - header is sent https://codesandbox.io/s/axios018-8fg9d 0.19 - header is not sent https://codesandbox.io/s/axios019-5ddn8

[jasonsaayman]

@glebtv this seems to in fact be intended. The documentation might need a bit of adjustment for this, I will have a look at it, however, it seems you may need to implement this:

instance.defaults.headers.common['Authorization'] = AUTH_TOKEN;

This will change the instance defaults rather than the global default. This makes sense, especially in this example.