- spec: XRPLF/XRPL-Standards#220
- amendment: "DeepFreeze"
- implemented deep freeze spec to allow token issuers to prevent currency holders from being able to acquire more of these tokens.
- in combination with normal freeze, deep freeze effectively prevents any balance trust line balance change of a currency holder (except direct issuer <-> holder payments).
- added 2 new invariant checks to verify that deep freeze cannot be enacted without normal freeze and transfer is not frozen.
- made some fixes to existing freeze handling.
Co-authored-by: Ed Hennis <ed@ripple.com>
Co-authored-by: Howard Hinnant <howard.hinnant@gmail.com>