In practice, presentation/display logic should be kept in UIs, but the core
api will need to duplicate a very small part of the code in DisplayUtils if
a very small part of this refactoring is not done. Instead of moving a tiny
bit of the volume formatting methods, all of them are moved to core.
We can cache an offer payload hash as soon as its `offerFeePaymentTxId`
is set. (The payload hash cannot be calculated until the object can
be transformed into a protobuf message, which requires a non-null
offerFeePaymentTxId.)
Another benefit is removal of the payload hash argument from the
`OfferBookListItem` constructor.
Changes include
- `OfferPayload` Added `transient byte[] hash` field + getter method
(where hash is calculated and cached).
- `OfferBookService` Removed `P2PDataStorage.ByteArray hashOfPayload`
parameter from `OfferBookChangedListener` listener methods
`onAdded` & `onRemoved`. (Hash is cached in `OfferPayload`.)
- `P2PDataStorage` Added null check to `ByteArray` class constructor.
- `OfferBook` Adjusted for change to `OfferBookChangedListener`.
Also removed redundant payload hash null checks.
- `TakeOfferDataModel` and `MarketAlerts` Adjusted for change to
`OfferBookChangedListener`.
- `OfferBookListItem` Removed overloaded constructor with
`@Nullable P2PDataStorage.ByteArray hashOfPayload` parameter.
(Field value is set from cached offer payload hash.)
- `OfferBookViewModelTest` and `OfferMaker` Adjusted test and test fixture:
do not attempt to create offer payloads without an `offerFeePaymentTxId`.
The new debug log statements included in this PR help trace add/remove
list item actions if problems are seen in the UI's OfferBook, after the
API 'editoffer' method is released.
They can and should be removed in a future PR if the released API feature
proves it did not introduce bugs into the UI.
Checking offer payload hashes in OfferBook's onAdded and onRemove methods
is sufficient to prevent incorrect removal of offer list items from the
UI OfferBook view (where api 'editoffer' causes onRemoved to be called
after onAdded on peers).
