A package that build depends on dh-go and runs "dh --with=golang" gets this,
and an override is the only way out:

  E: foo source: missing-build-dependency-for-dh-addon golang
     (does not satisfy dh-golang:any) [debian/rules]

dh-go ships the add-on (Debian/Debhelper/Sequence/golang.pm) but
add_ons.json only lists dh-golang, and dh-go conflicts with dh-golang. It
cannot provide dh-golang either, that would satisfy Build-Depends: dh-golang
for everyone else and dh-go builds in module mode.

The field already takes a list, see phpcomposer and single_binary:
--- a/data/debhelper/add_ons.json
+++ b/data/debhelper/add_ons.json
@@ -182,7 +182,8 @@
       },
       "golang" : {
          "installed_by" : [
-            "dh-golang"
+            "dh-golang",
+            "dh-go"
          ]
       },
       "grantlee" : {

Tried on a copy of /usr/share/lintian with a dh-go source package: tag gone
with the patch, back when I put the original file in the same tree.

Hello,

Bug #1151342 in lintian reported by you has been fixed in the
Git repository and is awaiting an upload. You can see the commit
message below and you can check the diff of the fix at:

https://salsa.debian.org/lintian/lintian/-/commit/f700d11a96af84afcc18547aaa08f578ba7b8280
------------------------------------------------------------------------
add_ons.json: Add dh-go for golang addon (Closes: #1151342)
------------------------------------------------------------------------

(this message was generated automatically)
-- 
Greetings

https://bugs.debian.org/1151342