There's a merged pull request on the void-packages repository

Openjdk 11
https://github.com/void-linux/void-packages/pull/13721

Description:
I'd much rather have @q66's solution (#3237) but this seems to build for at least x86_64, i686, aarch64.

This bootstraps openjdk-11 from openjdk-11-bin, which is the binary reference implementation.

Travis will fail because the builds take too long, but I've tested on my local machine and they build.