[Question] Creating a struct implementing MetaAPI

First of all thanks for maintaining these bindings, I am new to Rust, but worked with GStreamer a bit in the past. The ease of use and confidence I get in what I am writing is miles ahead of C code I used to write. Also, apologies if this is not the right place to ask this.

I am trying to implement a struct with the MetaAPI trait. However, I can't figure what is the GstType? Below is a minimal example:

struct StreamIdMeta {
    stream_id: u32,
}

unsafe impl MetaAPI for StreamIdMeta {
    type GstType = ???

    fn get_meta_api() -> glib::Type {
        glib::types::Type::U32
    }
}