Java: Add test for override of Map.put highlighting problem.

Author: aschackmull

java/ql/test/library-tests/frameworks/JaxWs/JakartaRsFlow.java

@@ -166,6 +166,10 @@ void testAbstractMultivaluedMap(Map<String, List<String>> map1, Map<String, List
     map2.put("key", list);
     AbstractMultivaluedMap<String, String> amm2 = new MyAbstractMultivaluedMapJak<String, String>(map2);
     sink(amm2.get("key").get(0)); // $ hasValueFlow
+
+    AbstractMultivaluedMap<String, String> amm3 = new MyAbstractMultivaluedMapJak<String, String>(null);
+    amm3.put("key", list);
+    sink(amm3.get("key").get(0)); // $ MISSING: hasValueFlow
   }
 
   void testMultivaluedHashMap(Map<String, String> map1, Map<String, String> map2,
@@ -407,4 +411,4 @@ void testUriBuilder() throws Exception {
 
 class DummyJakarta {
   private static Set<String> foo() { return null; }
-}
+}