"Extension 'ms-azuretools.vscode-bicep' uses a document selector without scheme." warning from vscode

in extension host output window:

2023-02-07 12:40:56.118 [info] Extension 'ms-azuretools.vscode-bicep' uses a document selector without scheme. Learn more about this: https://go.microsoft.com/fwlink/?linkid=872305

Start by reproducing the warning in the VS Code extension host output for the ms-azuretools.vscode-bicep extension. Trace the extension's document selector configuration and confirm the warning no longer appears; the issue does not name a source file or test to run.

Written by the indexing model from the issue text.