java: Generate overloaded non-optargs method for each optargs method.

For example the existing method:

  public void mkfs_opts (String fstype, String device, Map<..> optargs);

is now accompanied by this overloaded method which is a simple wrapper:

  public void mkfs_opts (String fstype, String device)
    throws LibGuestFSException
  {
    mkfs_opts (fstype, device, null);
  }

generator/generator_java.ml

@@ -178,6 +178,29 @@ public class GuestFS {
       );
       pr "  }\n";
       pr "\n";
+
+      (* Generate an overloaded method that has no optargs argument,
+       * and make it call the method above with 'null' for the last
+       * arg.
+       *)
+      if optargs <> [] then (
+        pr "  ";
+        generate_java_prototype ~public:true ~semicolon:false
+          name (ret, args, []);
+        pr "\n";
+        pr "  {\n";
+        (match ret with
+        | RErr -> pr "    "
+        | _ ->    pr "    return "
+        );
+        pr "%s (" name;
+        List.iter (fun arg -> pr "%s, " (name_of_argt arg)) args;
+        pr "null);\n";
+        pr "  }\n";
+        pr "\n"
+      );
+
+      (* Prototype for the native method. *)
       pr "  ";
       generate_java_prototype ~privat:true ~native:true name style;
       pr "\n";

java/examples/guestfs-java.pod

@@ -9,7 +9,7 @@ guestfs-java - How to use libguestfs from Java
  import com.redhat.et.libguestfs.*;
  
  GuestFS g = new GuestFS ();
- g.add_drive_opts ("disk.img", null);
+ g.add_drive_opts ("disk.img");
  g.launch ();
 
 =head1 DESCRIPTION

java/t/GuestFS080OptArgs.java

@@ -27,7 +27,7 @@ public class GuestFS080OptArgs
         try {
             GuestFS g = new GuestFS ();
 
-            g.add_drive_opts ("/dev/null", null);
+            g.add_drive_opts ("/dev/null");
 
             HashMap<String,Object> optargs;