`JAVA_OPTS` environment variable is not respected by the launcher (300USD Bounty)

[Baccata]

---

From the maintainer Li Haoyi: I'm putting a 300USD bounty on this issue, payable by bank transfer on a merged PR implementing this.

See https://github.com/orgs/com-lihaoyi/discussions/6 for other bounties and the terms and conditions that bounties operate under

---

Repro

In build.mill :

import mill._

def check = T.input { Runtime.getRuntime().maxMemory }

In .mill-version :

0.12.9

In terminal, run :

> JAVA_OPTS='-Xmx2G' mill -i show check
> JAVA_OPTS='-Xmx10G' mill -i show check

The printed value is the same.