Doh!

Author: jonpryor

src/Java.Interop/Java.Interop/JniObjectReferenceControlBlock.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Java.Interop;
+
+internal struct JniObjectReferenceControlBlock {
+	public	IntPtr  handle;
+	public  int     handle_type;
+	public  IntPtr  weak_handle;
+	public  int     refs_added;
+
+	public  static  readonly    int Size    = Marshal.SizeOf<JniObjectReferenceControlBlock>();
+
+	public  static  unsafe  IntPtr Alloc () =>
+		(IntPtr) NativeMemory.AllocZeroed (1, (uint) Size);
+
+	public  static  unsafe  void Free (ref IntPtr value)
+	{
+		if (value == 0) {
+			return;
+		}
+		NativeMemory.Free ((void*) value);
+		value   = IntPtr.Zero;
+	}
+}