RFR: 8323571: Regression in source resolution process [v2]

[Joe Wang]

> Fix a regression in the source resolution process where it failed to recognize a custom InputSource when both the public and system IDs are null. The particular issue is fixed at line 1233, the rest of the changes is formatting to make the null-check on InputSource the first.
> 
> Test is provided by Marc, thanks Marc! (https://github.com/junit-team/junit5/issues/3594)
> 
> XML tests, including the new test, pass with this change.

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

  Fix copyright year

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Changes:
  - all: https://git.openjdk.org/jdk/pull/17377/files
  - new: https://git.openjdk.org/jdk/pull/17377/files/2eb23440..010c5db8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17377&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17377&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/17377.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17377/head:pull/17377

PR: https://git.openjdk.org/jdk/pull/17377