RFR: 8323624: ProviderList.ServiceList does not need to be a list [v2]

[Weijun Wang]

> Re-implement it as an `Iterator` to make sure it can only be iterated once and make debugger happy.
> 
> No regression, just a refactoring.

Weijun Wang has updated the pull request incrementally with one additional commit since the last revision:

  : iterator

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/17381/files
  - new: https://git.openjdk.org/jdk/pull/17381/files/ce987768..58523048

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17381&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17381&range=00-01

  Stats: 60 lines in 12 files changed: 6 ins; 16 del; 38 mod
  Patch: https://git.openjdk.org/jdk/pull/17381.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17381/head:pull/17381

PR: https://git.openjdk.org/jdk/pull/17381