Plugins can affect the result of the get change / get change details
REST endpoints by:
* providing plugin defined attributes to the 'plugins' field in
ChangeInfo
* implementing a SubmitRule which affects the computation of
'submittable' field in ChangeInfo
If the plugin defined part of ChangeInfo depends on plugin specific
data, callers that use change ETags to avoid unneeded recomputations of
ChangeInfos may see outdated plugin attributes and/or outdated
submittable information, because a ChangeInfo is only reloaded if the
change ETag changes.
By implementating the new ChangeETagComputation interface plugins can
now contribute to the change ETag computation and thus ensure that the
ETag changes when the plugin data was changed. This way it can be
ensured that callers do not see outdated ChangeInfos.
Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: I358e3d4fb2145a164ec1387fc1b40778959ad41e
96915b72dd