Could you provide a build.gradle example configuration for a multiplatform common module?

[lamba92]

Multiplatform projects are cool. Multiplatform common code libraries are even more cool.
Kotlin standard library already uses Dokka for multiplatform common libraries. How do you configure Dokka and output jars?

[adam-arold]

This would be extremely good! The users of my library are complaining that they don't have a javadoc site to peruse, but I can't generate it without Dokka supporting this.

[ToxicBakery]

I have a working MPP project with Dokka. Unfortunately, I have been unable to determine how to fix classpath issues. This means that while the code in your library/application can be documented properly by Dokka, any libraries your code uses will result in ERROR CLASS as the class definition. If anyone has any tips I would be happy to try them. My best guess right now is that I need to manually point the classpath to the dependency jars however they are not available from the build dir so I would need to manually download the jars which is less than optimal.

Sample MPP project using a single module MPP setup with dokka and maven central
https://github.com/ToxicBakery/Arbor/blob/master/common/build.gradle

[fredgrott]

ToxicBakery first I like your setup so borrowing a few techniques from it ...I found this last week that corrects stuff for multimodule setups
http://asvid.github.io/android-build-hacks-3-documentation

[ToxicBakery]

@ShareMe so dependent libraries do not display the ERROR CLASS string? If so, which part of that referenced config is the relevant piece?

I suppose it's the Modules segment as that's where the author talks about the error class issue. I'll give that a go in my referenced project.

[ToxicBakery]

@ShareMe I gave that a go but I was still unable to determine how to properly configure the dependencies such that dokka is able to pull them in an prevent the ERROR CLASS messages.

[adam-arold]

@yole @semoro can you point us in the right direction for generating docs for MPP projects? I believe that this page was generated this way.

[rekire]

I cannot make it working for a MPP when I target JVM and JS. It just crashes with a NPE. The stacktrace it not helpful at all.

FAILURE: Build failed with an exception.

* What went wrong:
Could not determine the dependencies of task ':runtime-shared:dokka'.
> kotlin.KotlinNullPointerException (no error message)

* Try:
Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Exception is:
org.gradle.api.internal.tasks.TaskDependencyResolveException: Could not determine the dependencies of task ':runtime-shared:dokka'.
	at org.gradle.api.internal.tasks.CachingTaskDependencyResolveContext.getDependencies(CachingTaskDependencyResolveContext.java:68)
	at org.gradle.execution.plan.TaskDependencyResolver.resolveDependenciesFor(TaskDependencyResolver.java:46)
	at org.gradle.execution.plan.LocalTaskNode.getDependencies(LocalTaskNode.java:106)
	at org.gradle.execution.plan.LocalTaskNode.resolveDependencies(LocalTaskNode.java:79)
	at org.gradle.execution.plan.DefaultExecutionPlan.addEntryTasks(DefaultExecutionPlan.java:167)
	at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph.addEntryTasks(DefaultTaskExecutionGraph.java:139)
	at org.gradle.execution.TaskNameResolvingBuildConfigurationAction.configure(TaskNameResolvingBuildConfigurationAction.java:48)
	at org.gradle.execution.DefaultBuildConfigurationActionExecuter.configure(DefaultBuildConfigurationActionExecuter.java:57)
	at org.gradle.execution.DefaultBuildConfigurationActionExecuter.access$200(DefaultBuildConfigurationActionExecuter.java:26)
	at org.gradle.execution.DefaultBuildConfigurationActionExecuter$2.proceed(DefaultBuildConfigurationActionExecuter.java:63)
	at org.gradle.execution.DefaultTasksBuildExecutionAction.configure(DefaultTasksBuildExecutionAction.java:44)
	at org.gradle.execution.DefaultBuildConfigurationActionExecuter.configure(DefaultBuildConfigurationActionExecuter.java:57)
	at org.gradle.execution.DefaultBuildConfigurationActionExecuter.access$200(DefaultBuildConfigurationActionExecuter.java:26)
	at org.gradle.execution.DefaultBuildConfigurationActionExecuter$2.proceed(DefaultBuildConfigurationActionExecuter.java:63)
	at org.gradle.execution.ExcludedTaskFilteringBuildConfigurationAction.configure(ExcludedTaskFilteringBuildConfigurationAction.java:47)
	at org.gradle.execution.DefaultBuildConfigurationActionExecuter.configure(DefaultBuildConfigurationActionExecuter.java:57)
	at org.gradle.execution.DefaultBuildConfigurationActionExecuter.access$200(DefaultBuildConfigurationActionExecuter.java:26)
	at org.gradle.execution.DefaultBuildConfigurationActionExecuter$1.run(DefaultBuildConfigurationActionExecuter.java:43)
	at org.gradle.internal.Factories$1.create(Factories.java:25)
	at org.gradle.api.internal.project.DefaultProjectStateRegistry.withLenientState(DefaultProjectStateRegistry.java:132)
	at org.gradle.api.internal.project.DefaultProjectStateRegistry.withLenientState(DefaultProjectStateRegistry.java:124)
	at org.gradle.execution.DefaultBuildConfigurationActionExecuter.select(DefaultBuildConfigurationActionExecuter.java:39)
	at org.gradle.initialization.DefaultGradleLauncher$CalculateTaskGraph.run(DefaultGradleLauncher.java:333)
	at org.gradle.internal.operations.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:301)
	at org.gradle.internal.operations.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:293)
	at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:175)
	at org.gradle.internal.operations.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:91)
	at org.gradle.internal.operations.DelegatingBuildOperationExecutor.run(DelegatingBuildOperationExecutor.java:31)
	at org.gradle.initialization.DefaultGradleLauncher.constructTaskGraph(DefaultGradleLauncher.java:218)
	at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:155)
	at org.gradle.initialization.DefaultGradleLauncher.executeTasks(DefaultGradleLauncher.java:134)
	at org.gradle.internal.invocation.GradleBuildController$1.execute(GradleBuildController.java:58)
	at org.gradle.internal.invocation.GradleBuildController$1.execute(GradleBuildController.java:55)
	at org.gradle.internal.invocation.GradleBuildController$3.create(GradleBuildController.java:82)
	at org.gradle.internal.invocation.GradleBuildController$3.create(GradleBuildController.java:75)
	at org.gradle.internal.work.DefaultWorkerLeaseService.withLocks(DefaultWorkerLeaseService.java:183)
	at org.gradle.internal.work.StopShieldingWorkerLeaseService.withLocks(StopShieldingWorkerLeaseService.java:40)
	at org.gradle.internal.invocation.GradleBuildController.doBuild(GradleBuildController.java:75)
	at org.gradle.internal.invocation.GradleBuildController.run(GradleBuildController.java:55)
	at org.gradle.tooling.internal.provider.runner.BuildModelActionRunner.run(BuildModelActionRunner.java:54)
	at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildActionRunner.java:35)
	at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildActionRunner.java:35)
	at org.gradle.launcher.exec.BuildOutcomeReportingBuildActionRunner.run(BuildOutcomeReportingBuildActionRunner.java:58)
	at org.gradle.tooling.internal.provider.ValidatingBuildActionRunner.run(ValidatingBuildActionRunner.java:32)
	at org.gradle.launcher.exec.BuildCompletionNotifyingBuildActionRunner.run(BuildCompletionNotifyingBuildActionRunner.java:39)
	at org.gradle.launcher.exec.RunAsBuildOperationBuildActionRunner$3.call(RunAsBuildOperationBuildActionRunner.java:49)
	at org.gradle.launcher.exec.RunAsBuildOperationBuildActionRunner$3.call(RunAsBuildOperationBuildActionRunner.java:44)
	at org.gradle.internal.operations.DefaultBuildOperationExecutor$CallableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:315)
	at org.gradle.internal.operations.DefaultBuildOperationExecutor$CallableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:305)
	at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:175)
	at org.gradle.internal.operations.DefaultBuildOperationExecutor.call(DefaultBuildOperationExecutor.java:101)
	at org.gradle.internal.operations.DelegatingBuildOperationExecutor.call(DelegatingBuildOperationExecutor.java:36)
	at org.gradle.launcher.exec.RunAsBuildOperationBuildActionRunner.run(RunAsBuildOperationBuildActionRunner.java:44)
	at org.gradle.launcher.exec.InProcessBuildActionExecuter$1.transform(InProcessBuildActionExecuter.java:49)
	at org.gradle.launcher.exec.InProcessBuildActionExecuter$1.transform(InProcessBuildActionExecuter.java:46)
	at org.gradle.composite.internal.DefaultRootBuildState.run(DefaultRootBuildState.java:78)
	at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:46)
	at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:31)
	at org.gradle.launcher.exec.BuildTreeScopeBuildActionExecuter.execute(BuildTreeScopeBuildActionExecuter.java:42)
	at org.gradle.launcher.exec.BuildTreeScopeBuildActionExecuter.execute(BuildTreeScopeBuildActionExecuter.java:28)
	at org.gradle.tooling.internal.provider.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:78)
	at org.gradle.tooling.internal.provider.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:52)
	at org.gradle.tooling.internal.provider.SubscribableBuildActionExecuter.execute(SubscribableBuildActionExecuter.java:59)
	at org.gradle.tooling.internal.provider.SubscribableBuildActionExecuter.execute(SubscribableBuildActionExecuter.java:36)
	at org.gradle.tooling.internal.provider.SessionScopeBuildActionExecuter.execute(SessionScopeBuildActionExecuter.java:68)
	at org.gradle.tooling.internal.provider.SessionScopeBuildActionExecuter.execute(SessionScopeBuildActionExecuter.java:38)
	at org.gradle.tooling.internal.provider.GradleThreadBuildActionExecuter.execute(GradleThreadBuildActionExecuter.java:37)
	at org.gradle.tooling.internal.provider.GradleThreadBuildActionExecuter.execute(GradleThreadBuildActionExecuter.java:26)
	at org.gradle.tooling.internal.provider.ParallelismConfigurationBuildActionExecuter.execute(ParallelismConfigurationBuildActionExecuter.java:43)
	at org.gradle.tooling.internal.provider.ParallelismConfigurationBuildActionExecuter.execute(ParallelismConfigurationBuildActionExecuter.java:29)
	at org.gradle.tooling.internal.provider.StartParamsValidatingActionExecuter.execute(StartParamsValidatingActionExecuter.java:60)
	at org.gradle.tooling.internal.provider.StartParamsValidatingActionExecuter.execute(StartParamsValidatingActionExecuter.java:32)
	at org.gradle.tooling.internal.provider.SessionFailureReportingActionExecuter.execute(SessionFailureReportingActionExecuter.java:55)
	at org.gradle.tooling.internal.provider.SessionFailureReportingActionExecuter.execute(SessionFailureReportingActionExecuter.java:41)
	at org.gradle.tooling.internal.provider.SetupLoggingActionExecuter.execute(SetupLoggingActionExecuter.java:48)
	at org.gradle.tooling.internal.provider.SetupLoggingActionExecuter.execute(SetupLoggingActionExecuter.java:32)
	at org.gradle.launcher.daemon.server.exec.ExecuteBuild.doBuild(ExecuteBuild.java:67)
	at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:36)
	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
	at org.gradle.launcher.daemon.server.exec.WatchForDisconnection.execute(WatchForDisconnection.java:37)
	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
	at org.gradle.launcher.daemon.server.exec.ResetDeprecationLogger.execute(ResetDeprecationLogger.java:26)
	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
	at org.gradle.launcher.daemon.server.exec.RequestStopIfSingleUsedDaemon.execute(RequestStopIfSingleUsedDaemon.java:34)
	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
	at org.gradle.launcher.daemon.server.exec.ForwardClientInput$2.call(ForwardClientInput.java:74)
	at org.gradle.launcher.daemon.server.exec.ForwardClientInput$2.call(ForwardClientInput.java:72)
	at org.gradle.util.Swapper.swap(Swapper.java:38)
	at org.gradle.launcher.daemon.server.exec.ForwardClientInput.execute(ForwardClientInput.java:72)
	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
	at org.gradle.launcher.daemon.server.exec.LogAndCheckHealth.execute(LogAndCheckHealth.java:55)
	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
	at org.gradle.launcher.daemon.server.exec.LogToClient.doBuild(LogToClient.java:62)
	at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:36)
	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
	at org.gradle.launcher.daemon.server.exec.EstablishBuildEnvironment.doBuild(EstablishBuildEnvironment.java:81)
	at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:36)
	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:104)
	at org.gradle.launcher.daemon.server.exec.StartBuildOrRespondWithBusy$1.run(StartBuildOrRespondWithBusy.java:50)
	at org.gradle.launcher.daemon.server.DaemonStateCoordinator$1.run(DaemonStateCoordinator.java:295)
	at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:63)
	at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:46)
	at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:55)
Caused by: kotlin.KotlinNullPointerException
	at org.jetbrains.dokka.ReflectDsl$CallOrPropAccess.v(ReflectDsl.kt:32)
	at org.jetbrains.dokka.ReflectDsl$CallOrPropAccess.get(ReflectDsl.kt:20)
	at org.jetbrains.dokka.gradle.DokkaTask.extractClasspathAndSourceRootsFromKotlinTasks(main.kt:239)
	at org.jetbrains.dokka.gradle.DokkaTask.getInputFiles(main.kt:369)
	at org.gradle.api.internal.tasks.properties.bean.AbstractNestedRuntimeBeanNode$DefaultPropertyValue$1$1.create(AbstractNestedRuntimeBeanNode.java:82)
	at org.gradle.util.SingleMessageLogger.whileDisabled(SingleMessageLogger.java:341)
	at org.gradle.api.internal.tasks.properties.bean.AbstractNestedRuntimeBeanNode$DefaultPropertyValue$1.get(AbstractNestedRuntimeBeanNode.java:79)
	at com.google.common.base.Suppliers$NonSerializableMemoizingSupplier.get(Suppliers.java:167)
	at org.gradle.api.internal.tasks.properties.bean.AbstractNestedRuntimeBeanNode$DefaultPropertyValue.getValue(AbstractNestedRuntimeBeanNode.java:145)
	at org.gradle.api.internal.tasks.properties.bean.AbstractNestedRuntimeBeanNode$DefaultPropertyValue.call(AbstractNestedRuntimeBeanNode.java:158)
	at org.gradle.util.GUtil.uncheckedCall(GUtil.java:459)
	at org.gradle.api.internal.file.collections.BuildDependenciesOnlyFileCollectionResolveContext.add(BuildDependenciesOnlyFileCollectionResolveContext.java:64)
	at org.gradle.api.internal.tasks.TaskPropertyFileCollection.visitContents(TaskPropertyFileCollection.java:53)
	at org.gradle.api.internal.file.CompositeFileCollection.visitDependencies(CompositeFileCollection.java:186)
	at org.gradle.api.internal.tasks.CachingTaskDependencyResolveContext$TaskGraphImpl.getNodeValues(CachingTaskDependencyResolveContext.java:106)
	at org.gradle.internal.graph.CachingDirectedGraphWalker$GraphWithEmpyEdges.getNodeValues(CachingDirectedGraphWalker.java:211)
	at org.gradle.internal.graph.CachingDirectedGraphWalker.doSearch(CachingDirectedGraphWalker.java:121)
	at org.gradle.internal.graph.CachingDirectedGraphWalker.findValues(CachingDirectedGraphWalker.java:73)
	at org.gradle.api.internal.tasks.CachingTaskDependencyResolveContext.getDependencies(CachingTaskDependencyResolveContext.java:66)
	... 102 more

[KrystianUjma]

created by @kamilok1965 , we will link and merge it to kotlin dokka examples project after multiplatform release.