Get all workspace symbols from SourceKit-LSP

Is there a way to have SourceKit-LSP return all workspace symbols (across all files) for the workspace/symbol request — either as an undocumented parameter in an LSP request, or by implementing it myself in a fork of SourceKit-LSP? In the current implementation, a matching pattern is required; if I specify an empty string, I get back an empty array.

I've lightly looked into implementing this myself, but I'm not seeing any methods along the lines of forAllSymbols() in IndexStoreDB that I could use.