Imagine, in a project you are asked to consume a SOAP webservice. Yes, SOAP is aged as stone BUT it is also very precisely specified as an interface, which make it still a common choice when it comes to integrate systems. And only integrated systems deliver great benefit on the one hand as well as (old) legacy system have proven their business case which is why they are worth to integrate. (There is gold in legacy.)

So while integrating that SOAP webservice, you try to generate some Java classes from the XML files provided and suddenly, you see:

org.apache.cxf.tools.common.ToolException: Tools plugin provider jaxb context init failed

Welcome to the club, we found us in the very same situation.

While our sample project with an isolated setup and the following build.gradle was working fine, integrating it in our multi-project gradle build brought up the given error.

build.gradle of isolated, working, sample:

plugins {
	id 'java'
	id 'war'
	id 'org.springframework.boot' version '3.2.1'
	id 'io.spring.dependency-management' version '1.1.4'
	id 'com.github.seanrl.jaxb' version '2.5.1'
	id 'com.github.bjornvester.wsdl2java' version '2.0.2'
}

group = 'com.example'
version = '0.0.1-SNAPSHOT'

java {
	sourceCompatibility = '17'
}

repositories {
	mavenCentral()
}

ext {
	jaxbApiVersion = "2.2.7" //be careful with Jaxb version changes, xjc relies on it
	jaxbVersion = "2.3.5"
}

dependencies {
	implementation group: 'org.apache.httpcomponents', name: 'httpclient', version: '4.5.14'
	implementation 'org.springframework.boot:spring-boot-starter-web'
	implementation 'org.springframework.boot:spring-boot-starter-web-services'
	providedRuntime 'org.springframework.boot:spring-boot-starter-tomcat'
	testImplementation 'org.springframework.boot:spring-boot-starter-test'

	jaxb "com.sun.xml.bind:jaxb-xjc:$jaxbVersion"
	jaxb "com.sun.xml.bind:jaxb-impl:$jaxbVersion"
	jaxb "javax.xml.bind:jaxb-api:$jaxbApiVersion"
}

tasks.named('test') {
	useJUnitPlatform()
}

wsdl2java {
	cxfVersion.set("4.0.2")
	markGenerated.set(true)
	useJakarta.set(true)
	wsdlDir.set(layout.projectDirectory.dir("src/main/resources/service-schema/"))
	generatedSourceDir.set(layout.projectDirectory.dir("build/generated-sources/wsdl2java/"))
}

task copyGeneratedFilesToSourceFolder(type: Copy) {
	dependsOn 'wsdl2java'
	from "${project.buildDir}/generated-sources/wsdl2java"
	include "**/*.java"
	into "${project.projectDir}/src/main/java/"
}

But as i transferred this into the larger project, I got the error mentioned above:

org.apache.cxf.tools.common.ToolException: Tools plugin provider jaxb context init failed

To get more information, tried running my build with the --stacktrace flag, but it did not give a more detailed output or more hints than the error message above.

Going one step further with --debug, you find yourself flooded with an output - but having a closer look and going through it payed off. We find

[DEBUG] [jakarta.xml.bind] Unable to find from OSGi: [jakarta.xml.bind.JAXBContextFactory]
java.lang.ClassNotFoundException: org.glassfish.hk2.osgiresourcelocator.ServiceLoader
        at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:445)

Using some search-skills on this output, I add jaxb 'org.glassfish.hk2:hk2-api:3.1.0' to my build.gradle and get to a new output:

` org.apache.cxf.tools.common.ToolException: Could not find jaxb databinding within classpath`

which in turn leads me to the requirement of adding these to my dependencies:

    wsdl2java "org.apache.cxf:cxf-tools-wsdlto-frontend-jaxws:4.0.4"
    wsdl2java "org.apache.cxf:cxf-tools-wsdlto-databinding-jaxb:4.0.4"

and suddently I can see the output I was longing for:

BUILD SUCCESSFUL in 2s

Now, why did the transform from the simple sample project not work as expected? We found that the jaxb configuration in the gradle file above clashed with the things we previously had in our project. We replace the whole block with the newer glassfish dependencies:

    jaxb "org.glassfish.jaxb.core:4.0.5"
    jaxb 'org.glassfish.jaxb:jaxb-runtime:4.0.5'
    jaxb 'org.glassfish.jaxb:jaxb-xjc:4.0.5'
    jaxb 'org.glassfish.hk2:hk2-api:3.1.0'

To in essence, there is not enough tool support to make sure the dependency versions are compatible to each other and that might cause quite some headache.

Our receipt is, to build a minimal solution to the the desire feature working and then expande that working example step by step to make sure to only bring compatible things together.

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