Default host to nil for when there are no proxies.
Default host to nil for when there are no proxies.

- a reimplementation of https://github.com/cloudfoundry/cf-mysql-release/pull/108

[#121247455]

cloudfoundry/cf-mysql-release,cloudfoundry/cf-mysql-release,cloudfoundry/cf-mysql-release,cloudfoundry/cf-mysql-release