RFR: 8323624: ProviderList.ServiceList does not need to be a list [v5]

[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 with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since the last revision:

 - Merge branch 'master' into 8323624
 - Sean's comments
 - Merge branch 'master' into 8323624
 - rename class name
 - use consistent names
 - : iterator
 - the fix

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17381/files
  - new: https://git.openjdk.org/jdk/pull/17381/files/4cfc4c9b..0b2b49e8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17381&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17381&range=03-04

  Stats: 448113 lines in 3896 files changed: 31304 ins; 89900 del; 326909 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