RFR: 7088: Show concurrent option showing lesser number of records. [v2]

[Henrik Dafgård]

> Due to how StreamBackedItemCollections differ from EventCollections we can't rely on the assumption made that disjoint events are sorted in each IItemIterable. And since the classes aren't visible from RulesToolkit we have to look at the class name like this.

Henrik Dafgård has updated the pull request incrementally with one additional commit since the last revision:

  Add comment with issue reference

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Changes:
  - all: https://git.openjdk.java.net/jmc/pull/208/files
  - new: https://git.openjdk.java.net/jmc/pull/208/files/661db8a2..289e5844

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jmc&pr=208&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jmc&pr=208&range=00-01

  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jmc/pull/208.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/208/head:pull/208

PR: https://git.openjdk.java.net/jmc/pull/208