diff --git a/src/main/java/org/springframework/data/elasticsearch/core/DocumentAdapters.java b/src/main/java/org/springframework/data/elasticsearch/core/DocumentAdapters.java
index dd44763d6..9315da5c2 100644
--- a/src/main/java/org/springframework/data/elasticsearch/core/DocumentAdapters.java
+++ b/src/main/java/org/springframework/data/elasticsearch/core/DocumentAdapters.java
@@ -385,7 +385,7 @@ class DocumentAdapters {
 		 */
 		@Override
 		public String toString() {
-			return getClass().getSimpleName() + "@" + this.id + "#" + this.version + " " + toJson();
+			return getClass().getSimpleName() + '@' + this.id + '#' + this.version + ' ' + toJson();
 		}
 
 		@Nullable