How to suppress "source-is-missing" lintian error?

["A. Lewenberg" <deb251@lewenberg.com>]

I am trying to suppress some lintian errors in my package build. I see 
this error when running lintian:
--
E: stanford-spdb source: source-is-missing 
usr/share/spdb/vendor/assets/javascripts/bootstrap-4.4.1.min.js
--

I attempt to override this by adding to debian/lintian-overrides the line
--
stanford-spdb source: source-is-missing 
usr/share/spdb/vendor/assets/javascripts/bootstrap-4.4.1.min.js
--

I rebuild and run lintian again, but then I see this error:
--
E: stanford-spdb: malformed-override Override of source-is-missing for 
package type source (expecting binary)
--

So I try changing the line in lintian-overrides to
--
stanford-spdb binary: source-is-missing 
usr/share/spdb/vendor/assets/javascripts/bootstrap-4.4.1.min.js
--

Rebuilding the pcakge and running lintian now results in the error
--
E: stanford-spdb source: source-is-missing 
usr/share/spdb/vendor/assets/javascripts/bootstrap-4.4.1.min.js
--

Also, the line gets flagged as an unused override.

How do I get lintian to be quiet about this?