Gradle POM-only dependencies cause jar application loader to fail

[DanielThomas]

Dependencies with pom packaging are included on the classpath and the boot jar process nor the loader considers the type of the file cause application startup to fail.

To reproduce take the following build:

plugins {
	id 'org.springframework.boot' version '2.1.3.RELEASE'
	id 'java'
}

repositories {
	mavenCentral()
}

dependencies {
	compile 'com.googlecode.matrix-toolkits-java:mtj:1.0.3'
}

bootJar {
	mainClassName = 'com.example.ExampleApplication'
}

Run bootJar and run java -jar build/libs/spring.jar and note the failure:

Exception in thread "main" java.lang.IllegalStateException: Failed to get nested archive for entry BOOT-INF/lib/all-1.1.2.pom
	at org.springframework.boot.loader.archive.JarFileArchive.getNestedArchive(JarFileArchive.java:108)
	at org.springframework.boot.loader.archive.JarFileArchive.getNestedArchives(JarFileArchive.java:86)
	at org.springframework.boot.loader.ExecutableArchiveLauncher.getClassPathArchives(ExecutableArchiveLauncher.java:70)
	at org.springframework.boot.loader.Launcher.launch(Launcher.java:49)
	at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51)
Caused by: java.io.IOException: Unable to open nested jar file 'BOOT-INF/lib/all-1.1.2.pom'
	at org.springframework.boot.loader.jar.JarFile.getNestedJarFile(JarFile.java:256)
	at org.springframework.boot.loader.jar.JarFile.getNestedJarFile(JarFile.java:241)
	at org.springframework.boot.loader.archive.JarFileArchive.getNestedArchive(JarFileArchive.java:103)
	... 4 more
Caused by: java.io.IOException: Unable to find ZIP central directory records after reading 4270 bytes
	at org.springframework.boot.loader.jar.CentralDirectoryEndRecord.<init>(CentralDirectoryEndRecord.java:65)
	at org.springframework.boot.loader.jar.CentralDirectoryParser.parse(CentralDirectoryParser.java:52)
	at org.springframework.boot.loader.jar.JarFile.<init>(JarFile.java:123)
	at org.springframework.boot.loader.jar.JarFile.<init>(JarFile.java:111)
	at org.springframework.boot.loader.jar.JarFile.createJarFileFromFileEntry(JarFile.java:289)
	at org.springframework.boot.loader.jar.JarFile.createJarFileFromEntry(JarFile.java:264)
	at org.springframework.boot.loader.jar.JarFile.getNestedJarFile(JarFile.java:252)
	... 6 more

POM files can be expected on configurations for either pom packaged dependencies like this, or for pom dependency management files for new native BOM support.

Gradle version:

------------------------------------------------------------
Gradle 5.1.1
------------------------------------------------------------

Build time:   2019-01-10 23:05:02 UTC
Revision:     3c9abb645fb83932c44e8610642393ad62116807

Kotlin DSL:   1.1.1
Kotlin:       1.3.11
Groovy:       2.5.4
Ant:          Apache Ant(TM) version 1.9.13 compiled on July 10 2018
JVM:          1.8.0_202 (Azul Systems, Inc. 25.202-b05)
OS:           Mac OS X 10.14.3 x86_64

[snicoll]

For the record, the Maven plugin seems to skip pom artifacts.

[wilkinsona]

We just package whatever is on the classpath, with directories going into BOOT-INF/classes and files into BOOT-INF/lib. It doesn't make much sense to me that Gradle apparently adds poms to the classpath, but if that's what it does I guess we'll have to filter them out.

[ljacomet]

Just as an FYI, from the linked Gradle issue, I did some investigation and found that pom files for dependencies with <type>pom</type are added to the Maven build classpath. Which matches the comment from Stéphane.
See this comment for details.

So Gradle is consistent with Maven there.

[wilkinsona]

I stand corrected. Thanks, @ljacomet. I'm also surprised that Maven behaves the way that it does, but there are probably good reasons for it of which I am ignorant. Our Maven support for building fat jars is already written in such a way that it'll ignore a pom. Our Gradle support has been updated in 59430a2 to behave the same way.

[ljacomet]

Same surprise, assumptions on the reasons and ignorance here 😉