Deprecated map fields not marked as deprecated in generated code

[okkero]

Consider the following message definition:

message Foo {
  uint32 foo = 1 [deprecated = true];
  repeated string bar = 2 [deprecated = true];
  map<uint32, string> baz = 3 [deprecated = true];
}

These fields are all deprecated, so you'd expect they would all get marked as #[deprecated] in the generated Rust code. However, only foo and bar get correctly marked, and baz does not:

#[derive(Clone, PartialEq, ::prost::Message)]
pub struct Foo {
    #[deprecated]
    #[prost(uint32, tag = "1")]
    pub foo: u32,
    #[deprecated]
    #[prost(string, repeated, tag = "2")]
    pub bar: ::prost::alloc::vec::Vec<::prost::alloc::string::String>,
    #[prost(map = "uint32, string", tag = "3")]
    pub baz: ::std::collections::HashMap<u32, ::prost::alloc::string::String>,
}