DNS resolver sometimes attempts reverse lookup

[n-miles]

If you make a request to an IP address, the RequestHostnameResolver.resolve() method does a reverse lookup on that IP address to try to get a hostname out of it. This occurs on line 38:

final String hostname = unresolvedAddress.getHostName();

JavaDoc for InetSocketAddress.getHostName() says

    /**
     * Gets the {@code hostname}.
     * Note: This method may trigger a name service reverse lookup if the
     * address was created with a literal IP address.
     *
     * @return  the hostname part of the address.
     */

I'm guessing that this behavior is unintentional. I think that we actually want getHostString(), which says

    /**
     * Returns the hostname, or the String form of the address if it
     * doesn't have a hostname (it was created using a literal).
     * This has the benefit of <b>not</b> attempting a reverse lookup.
     *
     * @return the hostname, or String representation of the address.
     * @since 1.7
     */

There are several calls to getHostName() in other parts of the codebase that also look unintentional. @slandelle, any objections if I open a PR to switch this and all other occurrences to getHostString()?

[slandelle]

Sure!

[n-miles]

Opened #1633

[n-miles]

@slandelle when will this get put into a release?

[slandelle]

Next week.

[n-miles]

Awesome, thanks!

[slandelle]

@namiles I've just released 2.9.0, should be sync'ed on central in ~20min.