Window title field not available

In native lua i can do:
```
:lua vim.api.nvim_open_win(vim.api.nvim_create_buf(false, true), true, {relative='editor', width=50, height=10, row=5, col=10, style='minimal', border='rounded', zi
ndex=50, title='test', title_pos='center'})       
```

however via go plugin, this field is not available.