[Java] Fix Kryo FP & Kryo 5 Support

Closes #4992

java/ql/test/query-tests/security/CWE-502/KryoTest.java

@@ -0,0 +1,34 @@
+
+import java.io.*;
+import java.net.Socket;
+import com.esotericsoftware.kryo.Kryo;
+import com.esotericsoftware.kryo.pool.KryoPool;
+import com.esotericsoftware.kryo.io.Input;
+
+public class KryoTest {
+
+    private Kryo getSafeKryo() {
+        Kryo kryo = new Kryo();
+        kryo.setRegistrationRequired(true);
+        // ... kryo.register(A.class) ...
+        return kryo;
+    }
+
+    public void kryoDeserialize(Socket sock) throws java.io.IOException {
+        KryoPool kryoPool = new KryoPool.Builder(this::getSafeKryo).softReferences().build();
+        Input input = new Input(sock.getInputStream());
+        Object o = kryoPool.run(kryo -> kryo.readClassAndObject(input)); // OK
+    }
+
+    public void kryoDeserialize2(Socket sock) throws java.io.IOException {
+        KryoPool kryoPool = new KryoPool.Builder(this::getSafeKryo).softReferences().build();
+        Input input = new Input(sock.getInputStream());
+        Kryo k = kryoPool.borrow();
+        try {
+            Object o = k.readClassAndObject(input); // OK
+        } finally {
+            kryoPool.release(k);
+        }
+    }
+
+}