Property changed signal is only generated for properties with setter method

Using zbus v2.0.0-beta.3, the following code doesn't compile unless the set_prop() method is uncommented.

use zbus::dbus_interface;

struct Smth;

#[dbus_interface(name = "org.example.Smth")]
impl Smth {
    #[dbus_interface(property)]
    pub fn prop(&self) -> i32 {
        unimplemented!()
    }

    /*
    #[dbus_interface(property)]
    pub fn set_prop(&mut self, _prop: i32) {
        unimplemented!()
    }
    */
}

fn main() {
    let smth = Smth;
    smth.prop_changed().unwrap();
}

With the following error output.

error[E0599]: no method named `prop_changed` found for struct `Smth` in the current scope
  --> src/main.rs:22:10
   |
3  | struct Smth;
   | ------------ method `prop_changed` not found for this
...
22 |     smth.prop_changed().unwrap();
   |          ^^^^^^^^^^^^ method not found in `Smth`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0599`.