Fix issue jetty#5499

this PR let the ByteAccumulator recyclable. after invoke ByteAccumulator.transferTo method
we can invoke ByteAccumulator.recycle method to reuse byte[] via ByteAccumulator.newByteArray method

Signed-off-by: Baoyi Chen <chen.bao.yi@qq.com>

jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/extensions/compress/ByteAccumulator.java

@@ -103,7 +103,18 @@ void recycle()
     {
         index = 0;
         length = 0;
-        prevChunks = nextChunks;
+
+        int resize = 16;
+        if (prevChunks == null || nextChunks.size() > prevChunks.size())
+        {
+            prevChunks = nextChunks;
+        }
+
+        // keep prevChunks retain max resize elements
+        if (prevChunks.size() > resize) 
+        {
+            prevChunks.subList(resize, prevChunks.size()).clear();
+        }
         nextChunks = new ArrayList<>();
     }
 }