Fix names of nested inheritors (Kotlin#2188)

plugins/base/src/main/kotlin/translators/documentables/DefaultPageCreator.kt

@@ -197,7 +197,7 @@ open class DefaultPageCreator(
                     }),
                     children = map.entries.flatMap { entry -> entry.value.map { Pair(entry.key, it) } }
                         .groupBy({ it.second }, { it.first }).map { (classlike, platforms) ->
-                            val label = classlike.classNames?.substringBeforeLast(".") ?: classlike.toString()
+                            val label = classlike.classNames?.substringAfterLast(".") ?: classlike.toString()
                                 .also { logger.warn("No class name found for DRI $classlike") }
                             buildGroup(
                                 setOf(classlike),

plugins/base/src/test/kotlin/renderers/html/CoverPageTest.kt

@@ -0,0 +1,47 @@
+package renderers.html
+
+import org.jetbrains.dokka.base.testApi.testRunner.BaseAbstractTest
+import org.junit.jupiter.api.Test
+import signatures.renderedContent
+import utils.TestOutputWriterPlugin
+import kotlin.test.assertEquals
+
+class CoverPageTest : BaseAbstractTest() {
+
+    private val configuration = dokkaConfiguration {
+        sourceSets {
+            sourceSet {
+                sourceRoots = listOf("src/")
+                classpath = listOf(commonStdlibPath!!)
+                externalDocumentationLinks = listOf(stdlibExternalDocumentationLink)
+            }
+        }
+    }
+
+    @Test
+    fun `names of nested inheritors`() {
+        val source = """
+            |/src/main/kotlin/test/Test.kt
+            |package example
+            |
+            | sealed class Result{
+            |   class Success(): Result()
+            |   class Failed(): Result()
+            | }
+            """
+        val writerPlugin = TestOutputWriterPlugin()
+
+        testInline(
+            source,
+            configuration,
+            pluginOverrides = listOf(writerPlugin)
+        ) {
+            renderingStage = { _, _ ->
+                val content = writerPlugin.writer.renderedContent("root/example/-result/index.html")
+                val tableInheritors = content.select("div.table[data-togglable=Inheritors]").single()
+                assertEquals(tableInheritors.getElementsContainingOwnText("Failed").singleOrNull()?.tagName(), "a")
+                assertEquals(tableInheritors.getElementsContainingOwnText("Success").singleOrNull()?.tagName(), "a")
+            }
+        }
+    }
+}