Passing params as struct using derive-macro

Is there a way to pass method params through single struct (for sake of extensibility and flexibility), i.e. something like
```rust
#[rpc]
pub trait ServerApi {
    fn foo(&self, params: FooParams) -> Result<FooReply>;
}

struct FooParams {
    bar: String,
}
```

So now I can call `{"jsonrpc":"2.0","id":123,"method":"foo","params":{"bar": "buzz"}}`.