xml names can't have any of '[],' in them, which might appear in
generic type names. Truncate at the first '[' so the names are still valid.
Fixes#48318
Change-Id: I110ff4269f763089467e7cf84b0f0c5075fb44b7
Reviewed-on: https://go-review.googlesource.com/c/go/+/349349
Trust: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
