QT Creator complains about certain valid capabilities in the initialize message response from the Language Server.
When colorProvider is present (but false) the "General Messages" log says "Expected type Object but value contained Bool->colorProvider->capabilities".
When renameProvider is present with a prepareProvider the "General Messages" log says "Expected type Bool but value contained Object->renameProvider->capabilities".
See log for details.
(This is for an unreleased LS, using lsp4j, but the bugs seem to be general. I am not currently a Qt user, I only use Qt Creator for testing my language server.)