pub trait PropertyMap {
fn inner(&self) -> &HashMap<String, String>;
fn inner_mut(&mut self) -> &mut HashMap<String, String>;
fn is_empty(&self) -> bool { ... }
fn merge(&mut self, other: &Self) { ... }
fn get<K: ToString>(&self, key: K) -> Option<String> { ... }
fn set<K: ToString, V: ToString>(&mut self, key: K, value: V) { ... }
fn maybe_set<K: ToString, V: ToString>(&mut self, key: K, value: Option<V>) { ... }
fn get_entries(&self) -> Vec<(String, String)> { ... }
}