Import local schema to avoid DNS lookup in build

[jgneff]

This pull request changes two files to fix apache/netbeans#4920.

1. It modifies jakartaee_9.xsd to import the "xml:" namespace from a local copy of xml.xsd instead of importing it remotely from http://www.w3.org/2001/xml.xsd.
2. It replaces the local xml.xsd file with the latest version dated 2009-01 instead of the previous copy which seems to have been derived from the earliest version dated 2001-03.

Furthermore, I made the following changes to the xml.xsd file from the W3C:

• I removed the XML stylesheet because it causes a same-origin policy error in Firefox when viewing the file locally: "Error loading stylesheet: An unknown error has occurred (805303f4)."
• I added the current W3C Software and Document Notice and License as a comment formatted with an 80-character line length.
• I removed all trailing whitespace in the file.

How can I test this fix locally? I tried the following two test targets. The first one worked, but the second one failed.

$ ant -quiet -Dmetabuild.branch=release160 -Dcluster.config=release commit-validation
$ ant -quiet -Dmetabuild.branch=release160 -Dcluster.config=release test-basic

Let's add this to NetBeans 16 only if someone far more knowledgeable than I am about JavaEE and Jakarta can review and approve it. Otherwise, I have a workaround and can wait for the fix in NetBeans 17.

[neilcsmith-net]

Requested reviews and we'll see if we have a 16-rc4. Can you move the commit (rebase onto) delivery, so that it's possible to merge there if necessary. Actually, changed base is clean. Thanks!

[juneau001]

Looks like a good remedy to prevent Maven from trying to obtain the xml.xsd from the schema source location.

[mbien]

will we remember to do the same for the next xsd which is added? :)

[jgneff]

Actually, changed base is clean. Thanks!

Thanks, Neil. My local pull-request branch is also based off the delivery branch. I didn't notice that GitHub used the master branch as a base by default. Good to know.