Const
Ref: https://github.com/paritytech/polkadot-sdk/blob/bc53b9a03a742f8b658806a01a7bf853cb9a86cd/substrate/frame/nomination-pools/runtime-api/src/lib.rs#L26-L41
Ref: https://github.com/paritytech/polkadot-sdk/blob/bc53b9a03a742f8b658806a01a7bf853cb9a86cd/substrate/frame/nomination-pools/runtime-api/src/lib.rs#L26-L41