state_id-string, State identifier. Can be one of: "head" (canonical head in node's view), "genesis", "finalized", "justified", , <hex encoded stateRoot with 0x prefix>.
validator_id-string, Either hex encoded public key (any bytes48 with 0x prefix) or validator index
Example:
// Request
curl -X GET -H 'Content-Type: application/json'
https://ethereum-beacon.blockpi.network/rpc/v1/your-rpc-key/eth/v1/beacon/states/finalized/validators/0x8e323fd501233cd4d1b9d63d74076a38de50f2f584b001a5ac2412e4e46adb26d2fb2a6041e7e8c57cd4df0916729219
// Result
as described above
