[ARIES-1963] Use concurrent set
diff --git a/jax-rs.whiteboard/src/main/java/org/apache/aries/jax/rs/whiteboard/internal/AriesJaxrsServiceRuntime.java b/jax-rs.whiteboard/src/main/java/org/apache/aries/jax/rs/whiteboard/internal/AriesJaxrsServiceRuntime.java
index b24f026..9f3f48c 100644
--- a/jax-rs.whiteboard/src/main/java/org/apache/aries/jax/rs/whiteboard/internal/AriesJaxrsServiceRuntime.java
+++ b/jax-rs.whiteboard/src/main/java/org/apache/aries/jax/rs/whiteboard/internal/AriesJaxrsServiceRuntime.java
@@ -27,6 +27,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Map;
@@ -821,7 +822,7 @@
 
         return (__, collection) -> {
             if (collection == null) {
-                collection = new HashSet<>();
+                collection = Collections.newSetFromMap(new ConcurrentHashMap<>());
             }
 
             collection.add(t);