Extension class com.xxx.IDEA1CoverageRunner does not implement class com.intellij.coverage.CoverageRunner. It came from ExtensionComponentAdapt

Please provide more details like full stacktrace, plugin configuration and build files, etc.

build.gradle is as follows:

plugin.xml is as follows:

@Karol Lewandowski 

Please help me

full stacktrace is as follows:

java.lang.Throwable: Extension class com.xxx.IDEA1CoverageRunner does not implement class com.intellij.coverage.CoverageRunner. It came from ExtensionComponentAdapter[com.xxx.IDEA1CoverageRunner]: plugin=PluginDescriptor[name='demo', classpath='/Users/xujunhua/Downloads/build/idea-sandbox/plugins/demo']
    at com.intellij.openapi.diagnostic.Logger.error(Logger.java:134)
    at com.intellij.openapi.extensions.impl.ExtensionPointImpl.processAdapters(ExtensionPointImpl.java:267)
    at com.intellij.openapi.extensions.impl.ExtensionPointImpl.getExtensionList(ExtensionPointImpl.java:179)
    at com.intellij.openapi.extensions.ExtensionPointName.getExtensionList(ExtensionPointName.java:32)
    at com.intellij.coverage.BaseCoverageSuite.readRunnerAttribute(BaseCoverageSuite.java:97)
    at com.intellij.coverage.CoverageDataManagerImpl.readExternal(CoverageDataManagerImpl.java:153)
    at com.intellij.configurationStore.ComponentStoreImpl.initJdomExternalizable(ComponentStoreImpl.kt:307)
    at com.intellij.configurationStore.ComponentStoreImpl.initComponent(ComponentStoreImpl.kt:98)
    at com.intellij.configurationStore.ComponentStoreWithExtraComponents.initComponent(ComponentStoreWithExtraComponents.kt:15)
    at com.intellij.openapi.components.impl.PlatformComponentManagerImpl.initializeComponent(PlatformComponentManagerImpl.java:54)
    at com.intellij.openapi.components.impl.ComponentManagerImpl$ComponentConfigComponentAdapter.getComponentInstance(ComponentManagerImpl.java:484)
    at com.intellij.openapi.components.impl.ComponentManagerImpl.createComponents(ComponentManagerImpl.java:104)
    at com.intellij.openapi.components.impl.ComponentManagerImpl.init(ComponentManagerImpl.java:88)
    at com.intellij.openapi.project.impl.ProjectImpl.init(ProjectImpl.java:264)
    at com.intellij.openapi.project.impl.ProjectManagerImpl.initProject(ProjectManagerImpl.java:285)
    at com.intellij.openapi.project.impl.ProjectManagerImpl.lambda$loadProjectWithProgress$13(ProjectManagerImpl.java:553)
    at com.intellij.openapi.progress.impl.CoreProgressManager$1.run(CoreProgressManager.java:220)
    at com.intellij.openapi.progress.impl.CoreProgressManager$TaskRunnable.run(CoreProgressManager.java:727)
    at com.intellij.openapi.progress.impl.CoreProgressManager$5.run(CoreProgressManager.java:442)
    at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$runProcess$2(CoreProgressManager.java:164)
    at com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:582)
    at com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:532)
    at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:87)
    at com.intellij.openapi.progress.impl.CoreProgressManager.runProcess(CoreProgressManager.java:151)
    at com.intellij.openapi.application.impl.ApplicationImpl.lambda$null$10(ApplicationImpl.java:592)
    at com.intellij.openapi.application.impl.ApplicationImpl$1.run(ApplicationImpl.java:314)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

The Coverage plugin is bundled, so you shouldn't specify Gradle dependency for it.

Also, why do you specify dependencies to libraries from your IDE installation? You should specify only dependencies for external libraries. Other bundled libraries will be available to your code.

Please cleanup this at first. You can take a look at:
https://github.com/JetBrains/intellij-platform-plugin-template

as a reference for how to set up the plugin project.