Issue 7032: Implement Comparable on StreamCut & StreamCut.UNBOUNDED

[derekm]

Change log description
Adds Comparable<StreamCut> interface to StreamCut. Adds compareTo() methods to StreamCutImpl and StreamCut.UNBOUNDED.

Purpose of the change
Fixes #7032

What the code does
It allows StreamCuts to be compared as naturally ordered things being less-than (<), greater-than (>), or equal-to (=). Overlapping StreamCuts are not comparable and produce a RuntimeException.

How to verify it
./gradlew :client:test --tests io.pravega.client.stream.StreamCutTest

[derekm]

This is StreamCut.UNBOUNDED's compareTo(). UNBOUNDED is used to mean both "possibly ever-truncating stream head" AND "ever-extending stream tail", depending on argument position (whether it is used as a start streamcut or an end streamcut). Given that UNBOUNDED can refer to the head OR the tail, depending on where it is used, how should its compareTo() behave?

Should it be equal only to itself and greater-than all other streamcuts? (That is, should it represent the unbounded tail when compared to?)

[RaulGracia]

@derekm please, look this in case it is useful: #7032 (comment)
For consistency, I think it would be a good idea to have the same logic for comparing StreamCuts both in the client and the controller.

[tkaitchuck]

Derek's changes look good to me. I've added some additional changes, so I am going wider with review.

[codecov]

Codecov Report

Patch coverage: 86.36% and no project coverage change.

Comparison is base (05831c0) 86.35% compared to head (ea804f4) 86.36%.

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #7033   +/-   ##
=========================================
  Coverage     86.35%   86.36%           
- Complexity    16050    16068   +18     
=========================================
  Files          1031     1031           
  Lines         59815    59859   +44     
  Branches       6071     6086   +15     
=========================================
+ Hits          51655    51697   +42     
- Misses         4987     4989    +2     
  Partials       3173     3173           

Impacted Files	Coverage Δ
.../main/java/io/pravega/client/stream/StreamCut.java	84.21% <57.14%> (-15.79%)	⬇️
...a/io/pravega/client/stream/impl/StreamCutImpl.java	84.87% <91.89%> (+3.16%)	⬆️

... and 16 files with indirect coverage changes

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.