From cd873229b696fea522559658748f2f5871bd6a30 Mon Sep 17 00:00:00 2001
From: Kris De Volder <kdevolder@pivotal.io>
Date: Mon, 24 Jun 2019 11:11:01 -0700
Subject: [PATCH] textDocument/definition should not send 'null' result

See: https://github.com/spring-projects/sts4/issues/309
---
 .../languageserver/util/SimpleTextDocumentService.java      | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/headless-services/commons/commons-language-server/src/main/java/org/springframework/ide/vscode/commons/languageserver/util/SimpleTextDocumentService.java b/headless-services/commons/commons-language-server/src/main/java/org/springframework/ide/vscode/commons/languageserver/util/SimpleTextDocumentService.java
index 49b12e6f4..e2cc5c0d8 100644
--- a/headless-services/commons/commons-language-server/src/main/java/org/springframework/ide/vscode/commons/languageserver/util/SimpleTextDocumentService.java
+++ b/headless-services/commons/commons-language-server/src/main/java/org/springframework/ide/vscode/commons/languageserver/util/SimpleTextDocumentService.java
@@ -352,7 +352,11 @@ public class SimpleTextDocumentService implements TextDocumentService, DocumentE
 		if (h != null) {
 			return async.invoke(() -> {
 				List<Location> locations = h.handle(position);
-				return Either.<List<? extends Location>, List<? extends LocationLink>>forLeft(locations);
+				if (locations==null) {
+					// vscode client does not like to recieve null result. See: https://github.com/spring-projects/sts4/issues/309
+					locations = ImmutableList.of();
+				}
+				return Either.forLeft(locations);
 			});
 		}
 		return CompletableFuture.completedFuture(Either.forLeft(ImmutableList.of()));