java.lang.NoClassDefFoundError: scala/collection/convert/DecorateAsScala but scala-library in pom.xm-CodePudding

I am adding my first Swagger description to a trivial, working servlet built using RestEasy and deployed to a server using the current version of JBoss EAP. After adding many dependencies from sample pom.xml's including

        <dependency>
            <groupId>org.scala-lang</groupId>
            <artifactId>scala-library</artifactId>
            <version>2.13.7</version>
        </dependency>

I get the following stack trace. Please note I have also tried other versions of scala with the same result

1:17:18,353 ERROR [org.jboss.msc.service.fail] (ServerService Thread Pool -- 100) MSC000001: Failed to start service jboss.deployment.unit."PamHelper.war".undertow-deployment: org.jboss.msc.service.StartException in service jboss.deployment.unit."PamHelper.war".undertow-deployment: java.lang.NoClassDefFoundError: scala/collection/convert/DecorateAsScala
        at org.wildfly.extension.undertow@7.3.0.GA-redhat-00004//org.wildfly.extension.undertow.deployment.UndertowDeploymentService$1.run(UndertowDeploymentService.java:81)
        at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
        at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
        at org.jboss.threads@2.3.3.Final-redhat-00001//org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
        at org.jboss.threads@2.3.3.Final-redhat-00001//org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:1982)
        at org.jboss.threads@2.3.3.Final-redhat-00001//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1486)
        at org.jboss.threads@2.3.3.Final-redhat-00001//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1377)
        at java.base/java.lang.Thread.run(Thread.java:834)
        at org.jboss.threads@2.3.3.Final-redhat-00001//org.jboss.threads.JBossThread.run(JBossThread.java:485)
Caused by: java.lang.NoClassDefFoundError: scala/collection/convert/DecorateAsScala
        at java.base/java.lang.Class.getDeclaredMethods0(Native Method)
        at java.base/java.lang.Class.privateGetDeclaredMethods(Class.java:3166)
        at java.base/java.lang.Class.privateGetPublicMethods(Class.java:3191)
        at java.base/java.lang.Class.getMethods(Class.java:1904)
        at org.jboss.resteasy.resteasy-jaxrs@3.9.3.SP1-redhat-00001//org.jboss.resteasy.spi.metadata.ResourceBuilder.fromAnnotations(ResourceBuilder.java:861)
        at org.jboss.resteasy.resteasy-jaxrs@3.9.3.SP1-redhat-00001//org.jboss.resteasy.spi.metadata.ResourceBuilder.getRootResourceFromAnnotations(ResourceBuilder.java:830)
        at org.jboss.resteasy.resteasy-jaxrs@3.9.3.SP1-redhat-00001//org.jboss.resteasy.plugins.server.resourcefactory.POJOResourceFactory.<init>(POJOResourceFactory.java:38)
        at org.jboss.resteasy.resteasy-jaxrs@3.9.3.SP1-redhat-00001//org.jboss.resteasy.core.ResourceMethodRegistry.addPerRequestResource(ResourceMethodRegistry.java:79)
        at org.jboss.resteasy.resteasy-jaxrs@3.9.3.SP1-redhat-00001//org.jboss.resteasy.spi.ResteasyDeployment.registration(ResteasyDeployment.java:485)
        at org.jboss.resteasy.resteasy-jaxrs@3.9.3.SP1-redhat-00001//org.jboss.resteasy.spi.ResteasyDeployment.startInternal(ResteasyDeployment.java:282)
        at org.jboss.resteasy.resteasy-jaxrs@3.9.3.SP1-redhat-00001//org.jboss.resteasy.spi.ResteasyDeployment.start(ResteasyDeployment.java:89)
        at org.jboss.resteasy.resteasy-jaxrs@3.9.3.SP1-redhat-00001//org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap.contextInitialized(ResteasyBootstrap.java:25)
        at io.undertow.servlet@2.0.28.SP1-redhat-00001//io.undertow.servlet.core.ApplicationListeners.contextInitialized(ApplicationListeners.java:187)
        at io.undertow.servlet@2.0.28.SP1-redhat-00001//io.undertow.servlet.core.DeploymentManagerImpl$1.call(DeploymentManagerImpl.java:217)
        at io.undertow.servlet@2.0.28.SP1-redhat-00001//io.undertow.servlet.core.DeploymentManagerImpl$1.call(DeploymentManagerImpl.java:186)
        at io.undertow.servlet@2.0.28.SP1-redhat-00001//io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:42)
        at io.undertow.servlet@2.0.28.SP1-redhat-00001//io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
        at org.wildfly.extension.undertow@7.3.0.GA-redhat-00004//org.wildfly.extension.undertow.security.SecurityContextThreadSetupAction.lambda$create$0(SecurityContextThreadSetupAction.java:105)
        at org.wildfly.extension.undertow@7.3.0.GA-redhat-00004//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1504)
        at org.wildfly.extension.undertow@7.3.0.GA-redhat-00004//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1504)
        at org.wildfly.extension.undertow@7.3.0.GA-redhat-00004//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1504)
        at org.wildfly.extension.undertow@7.3.0.GA-redhat-00004//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1504)
        at io.undertow.servlet@2.0.28.SP1-redhat-00001//io.undertow.servlet.core.DeploymentManagerImpl.deploy(DeploymentManagerImpl.java:252)
        at org.wildfly.extension.undertow@7.3.0.GA-redhat-00004//org.wildfly.extension.undertow.deployment.UndertowDeploymentService.startContext(UndertowDeploymentService.java:96)
        at org.wildfly.extension.undertow@7.3.0.GA-redhat-00004//org.wildfly.extension.undertow.deployment.UndertowDeploymentService$1.run(UndertowDeploymentService.java:78)
        ... 8 more
Caused by: java.lang.ClassNotFoundException: scala.collection.convert.DecorateAsScala from [Module "deployment.PamHelper.war" from Service Module Loader]
        at org.jboss.modules.ModuleClassLoader.findClass(ModuleClassLoader.java:255)
        at org.jboss.modules.ConcurrentClassLoader.performLoadClassUnchecked(ConcurrentClassLoader.java:410)
        at org.jboss.modules.ConcurrentClassLoader.performLoadClass(ConcurrentClassLoader.java:398)
        at org.jboss.modules.ConcurrentClassLoader.loadClass(ConcurrentClassLoader.java:116)
        ... 33 more

I am taking my dependencies from postings that discuss using Swagger with RestEasy under JBoss, but this still seems to be a dependency issue. I don't see another scala dependency - what other dependency is needed for DecorateAsScala?

CodePudding user response：

scala.collection.convert.DecorateAsScala does not exist in Scala 2.13.7. You may want to try 2.12.15. Or even 2.11.12 if you run into similar errors then.

I wonder if you actually need a Scala dependency. None of the things you name seem to require Scala. Unless you want to use Swagger for Scala, but I guess that's not the case. Either way, if it is a transitive dependency Maven should automatically download the correct version if you don't declare it yourself.