code: public DocServiceBuilder injectedScriptSupplier(
              BiFunction<ServiceRequestContext, HttpRequest, String> supplier) {
          injectedScriptSuppliers.add(requireNonNull(supplier, "supplier"));
          return this;
      }
docs: Adds a supplier for Javascript scripts to inject into the {@code <head />} of the debug page HTML.
  The supplier will be called every request for the initial {@link DocService} HTML. This can be used to
  customize the debug page per-request (e.g., to provide a HeaderProvider for enabling authentication based
  on an injected timestamped token). All scripts are concatenated into the content of a single script tag.