Returns hash of block at given height in the most-work fully-validated chain.
heightnumberREQUIREDcurl --user myuser --data-binary '{"jsonrpc":"1.0","id":"1","method":"getblockhash","params":[1000]}' -H 'content-type:text/plain;' http://127.0.0.1:8332/"00000000c937983704a73af28acdec37b049d214adbda81d7e2a3dd146f6ed09"