ssphrase call if wallet is encrypted.
Note: This command is only compatible with legacy wallets.

Arguments:
1. newkeypool    (boolean, optional, default=true) Whether to flush old unused addresses, including change addresses, from the keypool and regenerate it.
                 If true, the next address from getnewaddress and change address from getrawchangeaddress will be from this new seed.
                 If false, addresses (including change addresses if the wallet already had HD Chain Split enabled) 