Add Integration Test for reproducible builds

[jorsol]

Signed-off-by: Jorge Solórzano jorsol@gmail.com

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[slawekjaranowski]

any hint why fail on jenkins on some nodes ...?
https://ci-maven.apache.org/blue/organizations/jenkins/Maven%2Fmaven-box%2Fmaven-javadoc-plugin/detail/master/28/pipeline

[jorsol]

any hint why fail on jenkins on some nodes ...? https://ci-maven.apache.org/blue/organizations/jenkins/Maven%2Fmaven-box%2Fmaven-javadoc-plugin/detail/master/28/pipeline

Oh my! those pesky bugs from javadoc.

On versions of java lower than 11.0.13, the -notimestamp does not work on index.html. See Bug JDK-8268771, on newer versions (11.0.13+) this was fixed, on Jenkins nodes the versions used are 11.0.12 on Linux and 11.0.11 on Windows, so this triggers the fail.

But even when using newer versions of java (11.0.13+), the second bug is the worst since it uses zipped index files, and the timestamp of the zipped files can change between runs, this is fixed on Java 15+ See Bug JDK-8237909. In other words, it's almost impossible to get reproducible javadoc jars on Java versions between 9 and 14. Also, this issue is not actually caught on the test, and that's why it passes on GH Actions (that use Java 11.0.15).

There is even a closed issue from Maven: https://issues.apache.org/jira/browse/MJAVADOC-681

I will open another PR that just skips versions between 9 and 14 since there is not much we can do.

[jorsol]

Skip version 9-14 and other small improvements: #155