Add WIP Java language bindings

src/bindings/java/ZeroTierFileDescriptorSet.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c)2013-2021 ZeroTier, Inc.
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file in the project's root directory.
+ *
+ * Change Date: 2026-01-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2.0 of the Apache License.
+ */
+/****/
+
+package com.zerotier.sdk;
+
+/**
+ * This class provides an fdset-like behavior to ZeroTierSocket
+ */
+class ZeroTierFileDescriptorSet {
+    byte[] fds_bits = new byte[1024];
+
+    /**
+     * Clear bit
+     */
+    public void CLR(int fd)
+    {
+        fds_bits[fd] = 0x00;
+    }
+
+    /**
+     * Check if bit is set
+     */
+    public boolean ISSET(int fd)
+    {
+        return fds_bits[fd] == 0x01;
+    }
+
+    /**
+     * Set bit
+     */
+    public void SET(int fd)
+    {
+        fds_bits[fd] = 0x01;
+    }
+
+    /**
+     * Zero-out all bits
+     */
+    public void ZERO()
+    {
+        for (int i = 0; i < 1024; i++) {
+            fds_bits[i] = 0x00;
+        }
+    }
+}