[clangd] switchSourceHeader uses null not empty string as sentinel.

As far as I can see, only theia actually implements this, and it expects null.

llvm-svn: 360119

1 files changed, 1 insertions, 1 deletions

diff --git a/clang-tools-extra/clangd/ClangdLSPServer.h b/clang-tools-extra/clangd/ClangdLSPServer.h
index 171ba075696..6603bedc5d6 100644
--- a/clang-tools-extra/clangd/ClangdLSPServer.h
+++ b/clang-tools-extra/clangd/ClangdLSPServer.h
@@ -85,7 +85,7 @@ private:
                         Callback<std::vector<Location>>);
   void onReference(const ReferenceParams &, Callback<std::vector<Location>>);
   void onSwitchSourceHeader(const TextDocumentIdentifier &,
-                            Callback<std::string>);
+                            Callback<llvm::Optional<std::string>>);
   void onDocumentHighlight(const TextDocumentPositionParams &,
                            Callback<std::vector<DocumentHighlight>>);
   void onFileEvent(const DidChangeWatchedFilesParams &);