implement HasPayload in terms of As{Ref,Mut}

src/requests/has_payload.rs

@@ -18,15 +18,19 @@ use crate::requests::Payload;
 /// [`BorrowMut`]: std::borrow::BorrowMut
 /// [`Payload`]: crate::requests::Payload
 /// [output]: HasPayload::Payload
-pub trait HasPayload {
+pub trait HasPayload: AsMut<<Self as HasPayload>::Payload> + AsRef<<Self as HasPayload>::Payload> {
     /// Type of the payload contained.
     type Payload: Payload;
 
     /// Gain mutable access to the underlying payload.
-    fn payload_mut(&mut self) -> &mut Self::Payload;
+    fn payload_mut(&mut self) -> &mut Self::Payload {
+        self.as_mut()
+    }
 
     /// Gain immutable access to the underlying payload.
-    fn payload_ref(&self) -> &Self::Payload;
+    fn payload_ref(&self) -> &Self::Payload {
+        self.as_ref()
+    }
 }
 
 impl<P> HasPayload for P
@@ -34,12 +38,4 @@ where
     P: Payload,
 {
     type Payload = Self;
-
-    fn payload_mut(&mut self) -> &mut Self::Payload {
-        self
-    }
-
-    fn payload_ref(&self) -> &Self::Payload {
-        self
-    }
 }

src/requests/payload.rs

@@ -6,7 +6,7 @@
 /// This trait provides some additional information needed for sending request
 /// to the telegram.
 #[cfg_attr(all(docsrs, feature = "nightly"), doc(spotlight))]
-pub trait Payload {
+pub trait Payload: AsMut<Self> + AsRef<Self> {
     /// Return type of the telegram method.
     ///
     /// Note: that should not include result wrappers (e.g. it should be simply