Fix another Jenkins build failure.
diff --git a/juneau-server/src/main/java/org/apache/juneau/server/RestServlet.java b/juneau-server/src/main/java/org/apache/juneau/server/RestServlet.java
index c0b5662..476964b 100755
--- a/juneau-server/src/main/java/org/apache/juneau/server/RestServlet.java
+++ b/juneau-server/src/main/java/org/apache/juneau/server/RestServlet.java
@@ -119,7 +119,7 @@
 	private String[] staticFilesPrefixes;

 	private ResponseHandler[] responseHandlers;

 	private String clientVersionHeader = "";

-	private Map<Locale,Swagger> swaggers = new ConcurrentHashMap<Locale,Swagger>();

+	private ConcurrentHashMap<Locale,Swagger> swaggers = new ConcurrentHashMap<Locale,Swagger>();

 

 	RestServletContext context;