diff --git a/core-common/src/main/java/org/glassfish/jersey/internal/util/collection/GuardianStringKeyMultivaluedMap.java b/core-common/src/main/java/org/glassfish/jersey/internal/util/collection/GuardianStringKeyMultivaluedMap.java
index 358a329fdd..1ca25499d2 100644
--- a/core-common/src/main/java/org/glassfish/jersey/internal/util/collection/GuardianStringKeyMultivaluedMap.java
+++ b/core-common/src/main/java/org/glassfish/jersey/internal/util/collection/GuardianStringKeyMultivaluedMap.java
@@ -381,6 +381,24 @@ public List<V> subList(int fromIndex, int toIndex) {
             final List<V> sublist = guarded.subList(fromIndex, toIndex);
             return sublist != null ? new GuardianList<>(sublist, guard) : sublist;
         }
+
+        @Override
+        public String toString() {
+            return guarded.toString();
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (GuardianList.class.isInstance(obj)) {
+                return guarded.equals(((GuardianList) obj).guarded);
+            }
+            return guarded.equals(obj);
+        }
+
+        @Override
+        public int hashCode() {
+            return guarded.hashCode();
+        }
     }
 
     private static class GuardianIterator<V> extends MutableGuardian<V> implements Iterator<V> {
@@ -411,6 +429,11 @@ public void remove() {
         public void forEachRemaining(Consumer<? super V> action) {
             guarded.forEachRemaining(action);
         }
+
+        @Override
+        public String toString() {
+            return guarded.toString();
+        }
     }
 
     private static class GuardianListIterator<V> extends GuardianIterator<V> implements ListIterator<V> {