Prevent Java 9 on Travis CI from failing

[sormuras]

Overview

Assume that two tests using Class::getPackage::getXyz() are not executed on Java 9 -- until the reason why those methods return null is understood and fixed. Create new ticket to track this issue?

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[sbrannen]

Let's not check that it is equal to 9-ea but rather that it starts with 9.

[sbrannen]

ditto

[sormuras]

Changes force pushed.

[sormuras]

Back to three green CI lights.

[sbrannen]

FYI: getPackage() is deprecated on JDK 9 in favor of getDefinedPackage().

So perhaps that's the reason.

But... getDefinedPackage() is not available until JDK 9.

[sbrannen]

Here's an excerpt from the JDK 9 mailing list:

I considered deprecating ClassLoader::getPackage(s). These methods are not doing anything inherently wrong or causing any risk although the spec and impl version, title, vendor, annotation might not be the expected value. The Package design and implementation has been flawed since 1.2. This patch leaves it with @apiNote to make it clear.

[sbrannen]

Oops... I linked to documentation about ClassLoader instead of Class. So Class::getPackage() is not deprecated in JDK 9; however, based on the linked discussion, it appears that package metadata still might suffer from the same issues as with ClassLoader.

[sbrannen]

And the Javadoc for Package states the following:

A Package can be obtained with the Package.getPackage(String) and ClassLoader.getDefinedPackage(String) methods. Every Package defined by a class loader can be obtained with the Package.getPackages() and ClassLoader.getDefinedPackages() methods.

[sbrannen]

And the following from the Javadoc for Package in JDK 9 seems to hit the nail on the head:

A Package automatically defined for classes in a named module has the following properties: ... The specification and implementation titles, versions, and vendors are unspecified.

So, since your test works with Object which is in the java.base module, I'm assuming the above applies, which means that the implementation titles, versions, and vendors are unspecified.

[sbrannen]

Create new ticket to track this issue?

Yes, we should create a new ticket to address the issue with package versioning metadata on JDK 9.

[sbrannen]

Merged into master.

Thanks

[sbrannen]

Created separate issue to address versioning metadata from JARs on Java 9 in #600.