Details
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New Feature
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Status: Closed
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Major
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Resolution: Incomplete
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2.2.1
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None
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None
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An issue in 2.2.1 but I think the same issue applies also to 3.0.
Description
There appears to be no official way to request usage of a particular Java library (such as a new release of JAXB) using the Java "endorsed" mechanism. The semantics would be very similar to provided scope except that the library is expected to override the JRE's boot classpath, both at compile time (main or test) and runtime (exec:exec and Surefire).
As investigated in https://netbeans.org/bugzilla/show_bug.cgi?id=185139#c8 there are various ways you can get this functionality to work in current Maven releases if you Google long enough, but all seem hackish. Prepending arguments to the bootclasspath directly is generally discouraged.
Manually configuring -endorseddirs (for javac) or -Djava.endorsed.dirs (for java incl. Surefire) seems to work, but you have to first download the endorsed libraries into some subdirectory of target, where they could consume considerable disk space.
You could fix the disk space issue by passing dirs in the local repository, but this requires hardcoding details of the ~/.m2/repository/ structure in the POM which is very ugly, and also means duplicating information about groupId, artifactId, and version (you still need to have artifacts declared elsewhere so they will get downloaded if not initially present).
Anyway all these tricks obscure the relatively simple intent of the developer, which is to use a given artifact in the project in preference to any equivalent in the current JRE. It is important to have a standardized way of declaring such dependencies, not just to make it easy to write and maintain pom.xml, but so that IDEs and other tools know what you intend to do and can (for example) offer appropriate code completion without reverse engineering various idioms.
Much preferable would be to simply declare these dependencies in the normal POM section, but with <scope>endorsed</scope>. Then maven-compiler-plugin, maven-exec-plugin, maven-surefire-plugin, etc. would need to be modified to understand these dependencies and use them appropriately when calling JDK tools. Plugin code could be smart enough to work optimally in the available environment; for example, if an artifact has only a single JAR in the local repository (no extra classifiers), the containing directory could be passed directly to JDK tools as an endorsed dir, but in other cases a target/endorsed dir could be generated and used instead.
One concern is that the notion of an endorsed library is quite specific to the JVM; Maven projects targeted at other platforms would presumably have no use for this scope. Perhaps this is not an issue.