diff --git a/platform/ide-core-impl/src/com/intellij/openapi/fileEditor/impl/UniqueNameEditorTabTitleProvider.kt b/platform/ide-core-impl/src/com/intellij/openapi/fileEditor/impl/UniqueNameEditorTabTitleProvider.kt
index c7222e2a3db4..dbb4ed4a40df 100644
--- a/platform/ide-core-impl/src/com/intellij/openapi/fileEditor/impl/UniqueNameEditorTabTitleProvider.kt
+++ b/platform/ide-core-impl/src/com/intellij/openapi/fileEditor/impl/UniqueNameEditorTabTitleProvider.kt
@@ -39,7 +39,7 @@ internal fun doGetUniqueNameEditorTabTitle(project: Project, file: VirtualFile):
 
   // Even though this is a 'tab title provider' it is used also when tabs are not shown, namely for building IDE frame title.
   val uniqueFilePathBuilder = UniqueVFilePathBuilder.getInstance()
-  var uniqueName = ReadAction.compute<String?, Throwable> {
+  var uniqueName = ReadAction.compute<String, Throwable> {
     if (uiSettings.editorTabPlacement == UISettings.TABS_NONE) {
       uniqueFilePathBuilder.getUniqueVirtualFilePath(project, file)
     }
diff --git a/platform/lang-impl/src/com/intellij/ide/util/gotoByName/GroupMapping.kt b/platform/lang-impl/src/com/intellij/ide/util/gotoByName/GroupMapping.kt
index be977898b1df..6a5f652275ca 100644
--- a/platform/lang-impl/src/com/intellij/ide/util/gotoByName/GroupMapping.kt
+++ b/platform/lang-impl/src/com/intellij/ide/util/gotoByName/GroupMapping.kt
@@ -24,7 +24,7 @@ class GroupMapping @JvmOverloads constructor(private val myShowNonPopupGroups: B
   }
 
   override fun compareTo(o: GroupMapping?): Int {
-    return Comparing.compare<String?>(this.firstGroupName, o?.firstGroupName)
+    return Comparing.compare(this.firstGroupName, o?.firstGroupName)
   }
 
   val bestGroupName: @ActionText String?
diff --git a/plugins/kotlin/fir/tests/test/org/jetbrains/kotlin/idea/fir/imports/ImportClassDuringTypingTest.kt b/plugins/kotlin/fir/tests/test/org/jetbrains/kotlin/idea/fir/imports/ImportClassDuringTypingTest.kt
index db41aab493e3..754ad2199f2a 100644
--- a/plugins/kotlin/fir/tests/test/org/jetbrains/kotlin/idea/fir/imports/ImportClassDuringTypingTest.kt
+++ b/plugins/kotlin/fir/tests/test/org/jetbrains/kotlin/idea/fir/imports/ImportClassDuringTypingTest.kt
@@ -51,7 +51,7 @@ class ImportClassDuringTypingTest: KotlinLightCodeInsightFixtureTestCase() {
         assertTrue(errDesc!!.getAction().isAvailable(getProject(), getEditor(), getFile()))
         for (i in error.getActualStartOffset()..<error.getActualEndOffset()) {
             getEditor().getCaretModel().moveToOffset(i)
-            val errDescriptors = ReadAction.nonBlocking<MutableList<IntentionActionDescriptor?>?>(Callable {
+            val errDescriptors = ReadAction.nonBlocking(Callable {
                 ShowIntentionsPass.getActionsToShow(getEditor(), getFile()).errorFixesToShow
             }).submit(AppExecutorUtil.getAppExecutorService()).get()
             val importDesc = errDescriptors.find{ descriptor ->
diff --git a/plugins/maven/src/main/java/org/jetbrains/idea/maven/execution/run/MavenShCommandLineState.kt b/plugins/maven/src/main/java/org/jetbrains/idea/maven/execution/run/MavenShCommandLineState.kt
index fe2fb908b962..9c905c0c3f17 100644
--- a/plugins/maven/src/main/java/org/jetbrains/idea/maven/execution/run/MavenShCommandLineState.kt
+++ b/plugins/maven/src/main/java/org/jetbrains/idea/maven/execution/run/MavenShCommandLineState.kt
@@ -222,7 +222,7 @@ class MavenShCommandLineState(val environment: ExecutionEnvironment, private val
   ): BuildView? {
     val console = createConsole()
     val project = myConfiguration.project
-    val viewManager = project.getService<ExternalSystemRunConfigurationViewManager?>(ExternalSystemRunConfigurationViewManager::class.java)
+    val viewManager = project.getService<ExternalSystemRunConfigurationViewManager>(ExternalSystemRunConfigurationViewManager::class.java)
     return object : BuildView(project, console, descriptor, "build.toolwindow.run.selection.state", viewManager) {
       override fun onEvent(buildId: Any, event: BuildEvent) {
         super.onEvent(buildId, event)
@@ -245,7 +245,7 @@ class MavenShCommandLineState(val environment: ExecutionEnvironment, private val
     processHandler: ProcessHandler,
   ): ExecutionResult {
     val consoleView = createConsole()
-    val viewManager = environment.project.getService<BuildViewManager?>(BuildViewManager::class.java)
+    val viewManager = environment.project.getService<BuildViewManager>(BuildViewManager::class.java)
 
     descriptor.withProcessHandler(MavenBuildHandlerFilterSpyWrapper(processHandler, isWrapperedOutput(), isWindows()), null)
     descriptor.withExecutionEnvironment(environment)
diff --git a/plugins/maven/src/main/java/org/jetbrains/idea/maven/utils/MavenUtil.kt b/plugins/maven/src/main/java/org/jetbrains/idea/maven/utils/MavenUtil.kt
index 0211e44c680b..d67f0c4188ab 100644
--- a/plugins/maven/src/main/java/org/jetbrains/idea/maven/utils/MavenUtil.kt
+++ b/plugins/maven/src/main/java/org/jetbrains/idea/maven/utils/MavenUtil.kt
@@ -1735,7 +1735,7 @@ object MavenUtil {
     val mavenProjectsManager = MavenProjectsManager.getInstance(project)
     if (mavenProjectsManager.findProject(file) != null) return true
 
-    return ReadAction.compute<Boolean?, RuntimeException?>(ThrowableComputable {
+    return ReadAction.compute<Boolean, RuntimeException>(ThrowableComputable {
       if (project.isDisposed()) return@ThrowableComputable false
       val psiFile = PsiManager.getInstance(project).findFile(file)
       if (psiFile == null) return@ThrowableComputable false