[UNDERTOW-2385] Modify ThreadLocalCache using WeakHashMap

core/src/main/java/io/undertow/server/DefaultByteBufferPool.java

@@ -26,9 +26,9 @@
 import java.nio.ByteBuffer;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
-import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.WeakHashMap;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
 
@@ -334,7 +334,7 @@ protected void finalize() throws Throwable {
     // class can be called by a different thread than the one that initialized the data.
     private static class ThreadLocalCache {
 
-        Map<Thread, ThreadLocalData> localsByThread = new HashMap<>();
+        Map<Thread, ThreadLocalData> localsByThread = new WeakHashMap<>();
 
         ThreadLocalData get() {
             return localsByThread.get(Thread.currentThread());