Flagging an issue for future reference, this was merged recently into relay:
https://github.com/facebook/relay/pull/2677
This will break importing here: https://github.com/relay-tools/relay-compiler-language-typescript/blob/master/src/TypeScriptGenerator.ts#L6
Happy to open PR when a new release is cut with this change.
Most helpful comment
this broke https://github.com/facebook/relay/issues/2710