OutgoingMessage -> dyn Publishable cast problem

build.log

$ cargo build
   Compiling wtf v0.1.0 (/Users/fey/wtf)
error[E0271]: type mismatch resolving `<impl core::future::future::Future as core::future::future::Future>::Output == std::result::Result<std::vec::Vec<std::boxed::Box<(dyn svc_agent::mqtt::Publishable + 'static)>>, std::string::String>`
  --> src/main.rs:11:22
   |
11 | async fn create() -> Result<Vec<Box<dyn Publishable>>, String> {
   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected struct `svc_agent::mqtt::OutgoingMessage`, found trait svc_agent::mqtt::Publishable
   |
   = note: expected type `std::result::Result<std::vec::Vec<std::boxed::Box<svc_agent::mqtt::OutgoingMessage<Data, svc_agent::mqtt::OutgoingResponseProperties>>>, _>`
              found type `std::result::Result<std::vec::Vec<std::boxed::Box<(dyn svc_agent::mqtt::Publishable + 'static)>>, std::string::String>`
   = note: the return type of a function must have a statically known size

error: aborting due to previous error

For more information about this error, try `rustc --explain E0271`.
error: Could not compile `wtf`.

To learn more, run the command again with --verbose.

Cargo.toml

[package]
name = "wtf"
version = "0.1.0"
authors = []
edition = "2018"

[dependencies]
serde = "1.0"
serde_derive = "1.0"

[dependencies.futures]
version = "=0.3.0-alpha.18"
package = "futures-preview"

[dependencies.svc-agent]
git = "https://github.com/netology-group/svc-agent-rs"
branch = "feature/ULMS-577"

main.rs

use futures::executor;
use serde_derive::Serialize;
use svc_agent::Destination;
use svc_agent::mqtt::{Publishable, OutgoingMessage, OutgoingResponseProperties, ResponseStatus};

#[derive(Debug, Serialize)]
struct Data {
    foo: String,
}

async fn create() -> Result<Vec<Box<dyn Publishable>>, String> {
    let message = OutgoingMessage {
        payload: Data { foo: "bar".to_string() },
        properties: OutgoingResponseProperties::new(ResponseStatus::OK, "whatever"),
        destination: Destination::Broadcast("nevermind".to_string()),
    };
    
    Ok(vec![Box::new(message)])
}

async fn run() -> Result<(), String> {
    let messages = create().await?;

    for message in messages.iter() {
        println!("{:?}", message.to_bytes());
    }

    Ok(())
}

fn main() {
    executor::block_on(run()).expect("Error running an executor");
}