How to show the welcome markdown file in editor when plugin is installed? Follow

Hello,

I'm trying to display a welcome markdown page on the editor when the plugin is installed using <postStartUpActivity>

Using TextEditorWithPreview.openPreviewForFile to display the markdown page in the editor on project startUp.

But, openPreviewForFile is shown as "Unresolved reference"

Is there any alternate that I can make use of to display the markdown page, when plugin is first installed?

Bellow is the code snippet which I'm using.

<postStartupActivity implementation="com.java.loaders.welcomePage"/>

class welcomePage: StartupActivity.DumbAware {
    override fun runActivity(project: Project) {
        val welcomeText = String(javaClass.getResourceAsStream("/Welcome/WelcomePage.md").readAllBytes())
        val welcomeFile = LightVirtualFile("Welcome Page", welcomeFile)
        invokeLater {
            TextEditorWithPreview.openPreviewForFile(project, welcomeFile)
        }
    }
}