Replace legacy collections with modern alternatives

Replace Stack with ArrayDeque in Networks.java for better performance by
removing unnecessary synchronization overhead. Replace Vector with ArrayList
in test code for consistency with modern Java practices.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: oschwald

src/main/java/com/maxmind/db/Networks.java

@@ -3,9 +3,10 @@
 import java.io.IOException;
 import java.net.Inet4Address;
 import java.net.InetAddress;
+import java.util.ArrayDeque;
 import java.util.Arrays;
+import java.util.Deque;
 import java.util.Iterator;
-import java.util.Stack;
 
 /**
  * Instances of this class provide an iterator over the networks in a database.
@@ -15,7 +16,7 @@
  */
 public final class Networks<T> implements Iterator<DatabaseRecord<T>> {
     private final Reader reader;
-    private final Stack<NetworkNode> nodes;
+    private final Deque<NetworkNode> nodes;
     private NetworkNode lastNode;
     private final boolean includeAliasedNetworks;
     private final Buffer buffer; /* Stores the buffer for Next() calls */
@@ -39,7 +40,7 @@ public final class Networks<T> implements Iterator<DatabaseRecord<T>> {
         this.reader = reader;
         this.includeAliasedNetworks = includeAliasedNetworks;
         this.buffer = reader.getBufferHolder().get();
-        this.nodes = new Stack<>();
+        this.nodes = new ArrayDeque<>();
         this.typeParameterClass = typeParameterClass;
         for (NetworkNode node : nodes) {
             this.nodes.push(node);

src/test/java/com/maxmind/db/ReaderTest.java

@@ -27,7 +27,6 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.Vector;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.stream.IntStream;
 
@@ -1397,12 +1396,12 @@ public void testDecodeVector(int chunkSize) throws IOException {
     }
 
     static class TestModelVector {
-        Vector<Long> arrayField;
+        ArrayList<Long> arrayField;
 
         @MaxMindDbConstructor
         public TestModelVector(
             @MaxMindDbParameter(name = "array")
-            Vector<Long> arrayField
+            ArrayList<Long> arrayField
         ) {
         this.arrayField = arrayField;
         }