RFR: 8323624: ProviderList.ServiceList does not need to be a list [v3]

[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:

  use consistent names

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17381/files
  - new: https://git.openjdk.org/jdk/pull/17381/files/58523048..cf3d124e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17381&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17381&range=01-02

  Stats: 6 lines in 2 files changed: 0 ins; 0 del; 6 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