Document that QueryParseException message is shown to end users

Change-Id: Ib2799757eaae4d2dff1edddc18fe62679097f1e1
diff --git a/gerrit-antlr/src/main/java/com/google/gerrit/server/query/QueryParseException.java b/gerrit-antlr/src/main/java/com/google/gerrit/server/query/QueryParseException.java
index 97eb2bf..1f69ba7 100644
--- a/gerrit-antlr/src/main/java/com/google/gerrit/server/query/QueryParseException.java
+++ b/gerrit-antlr/src/main/java/com/google/gerrit/server/query/QueryParseException.java
@@ -14,6 +14,11 @@
 
 package com.google.gerrit.server.query;
 
+/**
+ * Exception thrown when a search query is invalid.
+ * <p>
+ * <b>NOTE:</b> the message is visible to end users.
+ */
 public class QueryParseException extends Exception {
   private static final long serialVersionUID = 1L;