Java 9 Maven Plugin Support

[greenwoodma]

To allow the model to correctly generate XML descriptors under Java 9 when the code is run from within a Maven plugin we can't rely on package-info so we need to internalise all the info by adding -npa to the call to XJC. See openminted/omtd-share-annotations#45 for full details.

[reckart]

@greenwoodma why can we not rely on package-info?

[reckart]

Never mind ;) Answer is here: openminted/omtd-share-annotations#45 (comment)

[greenwoodma]

So I've now had the chance to try using 3.0.2-SNAPSHOT and I have good news and bad news.

The good news is that when running under Java 9 this version of the model produces a valid XML descriptor that validates against the XSD because XJC is run with the -npa option so as not to overwrite the custom details @courado added to package-info

The bad new is that under Java 9 the package-info classes are still completely ignored which means that the custom namespace prefix info in the hand crafted package-info.java files are ignored, so we end up with ns1: instead of ms: in the generated files.

While that's not ideal as you'll get different files when running under Java 8 and Java 9 both are valid given the XSD so that's probably good enough for me.

I guess that means we need to do a new release of the model which the maven plugin can then depend on.

[reckart]

Do you know if it is a known bug in Java 9 or JAXB that package-info is ignored? Do you have some issue tracker link?

[greenwoodma]

Unfortunately I've been unable to find any mention of what the actual problem is no matter what I google for. If anyone comes across anything I'd be interested in what they find, but for now as I said it just completely ignores the info in package-info but I don't know if the problem is in java 9, maven, or JAXB 2.3.0 unfortunately

[reckart]

• https://stackoverflow.com/questions/34264663/jaxb-package-info-java-declarations-are-ignored-in-separate-maven-modul

... overwrite the custom details @courado added to package-info

What custom details do you mean? The omtd-model-3.0.2.jar does not seem to include any package-info.classfiles?

[greenwoodma]

What custom details do you mean? The omtd-model-3.0.2.jar does not seem to include any package-info.classfiles?

So in omtd-model:3.0.2 there is a eu.openminted.registry.domain.package-info class generated by XJC (I've double checked the jar on central and the class is definitely there). It basically specifies the default namespace for all elements where it is not set in the Java class files in the same package. This file is ignored when run as parts of a maven plugin under Java 9 which is why the validation then fails as the prefix is missing from the XML elements (as described in the omtd-share-annotations issue)

In 3.0.2-SNAPSHOT (i.e. the develop branch which should really by 3.0.3-SNAPSHOT or something) there is actually a package-info.java in the main source tree as @courado has added explicit prefix mappings for the namespaces. Because of this custom file XJC is run with the -npa option so as not to generate it's own package-info.java files which would override the custom settings. This means that with 3.0.2-SNAPSHOT the namespace information is correctly embedded in the generated Java source files and hence works when used in the maven plugin under Java 9. The custom namespace prefix mappings are however missing in that situation because the package-info class is still ignored.

[reckart]

Right - found the package-info.class doing a grep over the JAR. Thanks again.