Honour ignoreOutsideDomain when set on its own in HostURLFilter

[rzo1]

HostURLFilter.configure() read the ignoreOutsideDomain parameter but tested the ignoreOutsideHost node for null. A configuration naming only ignoreOutsideDomain was silently discarded and the filter let every URL through; one naming only ignoreOutsideHost: false threw a NullPointerException at topology startup. ignoreOutsideHost: true was never affected, as it short-circuits before the domain parameter is read. Each parameter is now tested on its own.

Topologies setting only ignoreOutsideDomain: true will start restricting outlinks to the source domain, as configured. Configurations setting both keys, including all three archetypes, are unaffected.

For all changes

• Is there a issue associated with this PR? Is it referenced in the commit message? - no issue

• Does your PR title start with #XXXX where XXXX is the issue number you are trying to resolve? - no issue

• Has your PR been rebased against the latest commit within the target branch (typically main)?

• Is your initial contribution a single, squashed commit?

• Is the code properly formatted with mvn git-code-format:format-code -Dgcf.globPattern="**/*" -Dskip.format.code=false?

For code changes

• Have you ensured that the full suite of tests is executed via mvn clean verify? - core module tests only (348 run, all green)
• Have you written or updated unit tests to verify your changes? - two new cases in HostURLFilterTest, both fail without the fix
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[dpol1]

LGTM. One thing for the description: only ignoreOutsideHost: false on its own NPE'd, true never reached the domain branch. Worth being precise, since this and the "only ignoreOutsideDomain now restricts" sentence will end up in the 4.0 release notes.

[rzo1]

Both made precise: the NPE is now attributed to ignoreOutsideHost: false, with a note that true short-circuits before the domain parameter is ever read, and the second sentence is scoped to ignoreOutsideDomain: true. Commit message and description both updated.

[jnioche]

thanks @rzo1