To allow ProxyManager return null (or empty proxy) for not using a proxy for some specific requests

[chhsiao90]

What kind of issue is this?

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In our use case, we have our own ProxyManager implementation, we'd like to have the flexibility to use proxies for some requests, but no proxy for other cases.

[chhsiao90]

I'd like to create a PR for this.

[jnioche]

Yes please.
ProxyManager could return an Optional depending on the Metadata. The code in the protocol implementations would need changing accordingly