Adding Pallet-staking to frontier unresolved import `sc_rpc::Metadata`

Question

I have used frontier-node-template from parity tech repo to setup a private evm supported network. The network is running fine, authoring blocks and connecting with Metamask wallet for all functions. The next goal is to add pallet-staking to the same.

To achieve so, I am adding pallet-staking into Cargo.toml using paritytech/substrate using the following line.

pallet-staking = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }

Post adding this line it compiles upto a good bit but then throws errors in client/rpc module which has use sc_rpc:Metadata but is showing unresolved type Metadata. I can also see that it is available as struct in sc_rpc docs https://docs.rs/sc-rpc/latest/sc_rpc/struct.Metadata.html

I am using version 4.0.0-dev from https://github.com/paritytech/substrate master branch.

xxxx@ip-10-20-14-8:~/xxxx/frontier$ cargo check
    Checking fc-rpc v2.0.0-dev (/home/xxxx/xxxx/frontier/client/rpc)
error[E0432]: unresolved import `sc_rpc::Metadata`
  --> client/rpc/src/eth_pubsub.rs:38:5
   |
38 | use sc_rpc::Metadata;
   |     ^^^^^^^^^^^^^^^^ no `Metadata` in the root

For more information about this error, try `rustc --explain E0432`.
error: could not compile `fc-rpc` due to previous error

Please help on this error as to me it seems a dependency compatibility issue. Also, if any one has any reference to point to where substrate staking pallet with EVM pallet is running fine.