Change effective on 27 August 2018
Go version 1.11 is available and supported, but not yet the default. You can read about what is new in Go1.11 here. After more extensive testing Go 1.11 will becomes the default. At that time Go 1.9 will be deprecated.
Go 1.11’s big new feature is experimental support for Go Modules (wiki. We currently have basic module support available, but don’t currently believe it’s sufficiently stable for production use. Issues encountered while building with modules should be reported directly against the buildpack.