BlockId removal: refactor: Backend::body (#12587)

It changes the arguments of `Backend::body` method from: `BlockId<Block>` to: `&Block::Hash`

This PR is part of BlockId::Number refactoring analysis (paritytech/substrate#11292)

Co-authored-by: parity-processbot <>

substrate/primitives/blockchain/src/backend.rs

@@ -89,7 +89,7 @@ pub trait Backend<Block: BlockT>:
 	HeaderBackend<Block> + HeaderMetadata<Block, Error = Error>
 {
 	/// Get block body. Returns `None` if block is not found.
-	fn body(&self, id: BlockId<Block>) -> Result<Option<Vec<<Block as BlockT>::Extrinsic>>>;
+	fn body(&self, hash: &Block::Hash) -> Result<Option<Vec<<Block as BlockT>::Extrinsic>>>;
 	/// Get block justifications. Returns `None` if no justification exists.
 	fn justifications(&self, id: BlockId<Block>) -> Result<Option<Justifications>>;
 	/// Get last finalized block hash.