diff --git a/sbt-app/src/sbt-test/lm-coursier/config-deps-resolution/project/src/main/scala/sbt/MyPlugin.scala b/sbt-app/src/sbt-test/lm-coursier/config-deps-resolution/project/src/main/scala/sbt/MyPlugin.scala
index 816e06f4f..52cc29841 100644
--- a/sbt-app/src/sbt-test/lm-coursier/config-deps-resolution/project/src/main/scala/sbt/MyPlugin.scala
+++ b/sbt-app/src/sbt-test/lm-coursier/config-deps-resolution/project/src/main/scala/sbt/MyPlugin.scala
@@ -9,7 +9,7 @@ object MyPlugin extends AutoPlugin {
 
   val FooConfig = config("foo")
 
-  override def projectSettings = Seq[Setting[_]](
+  override def projectSettings = Seq[Setting[?]](
     libraryDependencies ++= Seq(
       "org.slf4j" % "slf4j-api" % "1.7.0",
       "ch.qos.logback" % "logback-classic" % "1.1.7"
diff --git a/sbt-app/src/sbt-test/plugins/hydra/project/HydraPlugin.scala b/sbt-app/src/sbt-test/plugins/hydra/project/HydraPlugin.scala
index 68d4ffa99..94a1fa53a 100644
--- a/sbt-app/src/sbt-test/plugins/hydra/project/HydraPlugin.scala
+++ b/sbt-app/src/sbt-test/plugins/hydra/project/HydraPlugin.scala
@@ -11,9 +11,9 @@ object HydraPlugin extends AutoPlugin {
     resolvers += "Triplequote Maven Releases" at "https://repo.triplequote.com/artifactory/libs-release/",
   ) ++ inConfig(Compile)(compileSettings) ++ inConfig(Test)(compileSettings)
 
-  private lazy val compileSettings: Seq[Def.Setting[_]] = inTask(compile)(compileInputsSettings)
+  private lazy val compileSettings: Seq[Def.Setting[?]] = inTask(compile)(compileInputsSettings)
   
-  private def compileInputsSettings: Seq[Setting[_]] = Seq(
+  private def compileInputsSettings: Seq[Setting[?]] = Seq(
     scalaCompilerBridgeSource := {
       ModuleID("com.triplequote", "hydra-bridge_1_0", "2.1.4")
         .withConfigurations(Some(Configurations.Compile.name))
diff --git a/sbt-app/src/sbt-test/plugins/twirl/project/TwirlPlugin.scala b/sbt-app/src/sbt-test/plugins/twirl/project/TwirlPlugin.scala
index 5911cdfcc..93b33dda2 100644
--- a/sbt-app/src/sbt-test/plugins/twirl/project/TwirlPlugin.scala
+++ b/sbt-app/src/sbt-test/plugins/twirl/project/TwirlPlugin.scala
@@ -9,13 +9,13 @@ object TwirlPlugin extends AutoPlugin {
     val twirlCompileTemplates = taskKey[Seq[File]]("Compile twirl templates into scala source files")
   }
 
-  override def projectSettings: Seq[Setting[_]] =
+  override def projectSettings: Seq[Setting[?]] =
     inConfig(Compile)(twirlSettings) ++
         inConfig(Test)(twirlSettings)
 
   import autoImport._
 
-  def twirlSettings: Seq[Setting[_]] =  Seq(
+  def twirlSettings: Seq[Setting[?]] =  Seq(
     twirlCompileTemplates / includeFilter := "*.scala.*",
     twirlCompileTemplates / excludeFilter := HiddenFileFilter,
     twirlCompileTemplates / sourceDirectories := Seq(sourceDirectory.value / "twirl"),
diff --git a/sbt-app/src/sbt-test/project/auto-import/project/P.scala b/sbt-app/src/sbt-test/project/auto-import/project/P.scala
index 70e309a38..ef621fa8b 100644
--- a/sbt-app/src/sbt-test/project/auto-import/project/P.scala
+++ b/sbt-app/src/sbt-test/project/auto-import/project/P.scala
@@ -21,7 +21,7 @@ package name.example {
     }
 
     import autoImport._
-    override def projectSettings = Seq[Setting[_]](
+    override def projectSettings = Seq[Setting[?]](
       checkMaxErrors := (Keys.maxErrors map { me => assert(me == xyz, "Expected maxErrors to be " + xyz + ", but it was " + me ) }).value,
       checkName := (Keys.name map { n => assert(n == "Demo", "Expected name to be 'Demo', but it was '" + n + "'" ) }).value
     )
diff --git a/sbt-app/src/sbt-test/project/auto-plugins-default-requires-jvmplugin/project/TestP.scala b/sbt-app/src/sbt-test/project/auto-plugins-default-requires-jvmplugin/project/TestP.scala
index a1c75e45b..a7a8edcd2 100644
--- a/sbt-app/src/sbt-test/project/auto-plugins-default-requires-jvmplugin/project/TestP.scala
+++ b/sbt-app/src/sbt-test/project/auto-plugins-default-requires-jvmplugin/project/TestP.scala
@@ -1,7 +1,7 @@
 import sbt._, Keys._
 
 object TestP extends AutoPlugin {
-  override def projectSettings: Seq[Setting[_]] = Seq(
+  override def projectSettings: Seq[Setting[?]] = Seq(
     Compile / resourceGenerators += Def.task {
       streams.value.log.info("resource generated in plugin")
       Seq.empty[File]
diff --git a/sbt-app/src/sbt-test/project/auto-plugins/project/A.scala b/sbt-app/src/sbt-test/project/auto-plugins/project/A.scala
index b11319afe..8ea97c1b3 100644
--- a/sbt-app/src/sbt-test/project/auto-plugins/project/A.scala
+++ b/sbt-app/src/sbt-test/project/auto-plugins/project/A.scala
@@ -18,7 +18,7 @@ object TopA extends AutoPlugin {
 
   override def trigger = AllRequirements
 
-  override def projectSettings: scala.Seq[sbt.Setting[_]] = Seq(
+  override def projectSettings: scala.Seq[sbt.Setting[?]] = Seq(
     topLevelDemo := s"TopA: topLevelDemo project ${name.value}",
     demo := s"TopA: demo project ${name.value}"
   )
@@ -31,7 +31,7 @@ object TopB extends AutoPlugin {
 
   val autoImport = TopLevelImports
 
-  override def projectSettings: Seq[Setting[_]] = Seq(
+  override def projectSettings: Seq[Setting[?]] = Seq(
     topLevelDemo := s"TopB: topLevelDemo project ${name.value}"
   )
 
diff --git a/sbt-app/src/sbt-test/project/auto-plugins/project/Q.scala b/sbt-app/src/sbt-test/project/auto-plugins/project/Q.scala
index a78327be9..310852ad8 100644
--- a/sbt-app/src/sbt-test/project/auto-plugins/project/Q.scala
+++ b/sbt-app/src/sbt-test/project/auto-plugins/project/Q.scala
@@ -48,16 +48,16 @@ object Q extends AutoPlugin {
     Quux ::
     Nil
 
-   override def projectSettings: Seq[Setting[_]] =
+   override def projectSettings: Seq[Setting[?]] =
     (demo := s"project ${name.value}") ::
     (Quux / del := " Q") ::
     Nil
 
-   override def buildSettings: Seq[Setting[_]] =
+   override def buildSettings: Seq[Setting[?]] =
     (demo := s"build ${buildCount.getAndIncrement}") ::
     Nil
 
-   override def globalSettings: Seq[Setting[_]] =
+   override def globalSettings: Seq[Setting[?]] =
     (demo := s"global ${globalCount.getAndIncrement}") ::
     Nil
 
diff --git a/sbt-app/src/sbt-test/project/extra-projects/project/DatabasePlugin.scala b/sbt-app/src/sbt-test/project/extra-projects/project/DatabasePlugin.scala
index 0d7a4163e..122822da6 100644
--- a/sbt-app/src/sbt-test/project/extra-projects/project/DatabasePlugin.scala
+++ b/sbt-app/src/sbt-test/project/extra-projects/project/DatabasePlugin.scala
@@ -8,7 +8,7 @@ object DatabasePlugin extends AutoPlugin {
     lazy val databaseName = settingKey[String]("name of the database")
   }
   import autoImport._
-  override def projectSettings: Seq[Setting[_]] =
+  override def projectSettings: Seq[Setting[?]] =
     Seq(
       databaseName := "something"
     )
diff --git a/sbt-app/src/sbt-test/project/extra-projects/project/ExtraProjectPluginExample2.scala b/sbt-app/src/sbt-test/project/extra-projects/project/ExtraProjectPluginExample2.scala
index dd1682623..ba8eae29c 100644
--- a/sbt-app/src/sbt-test/project/extra-projects/project/ExtraProjectPluginExample2.scala
+++ b/sbt-app/src/sbt-test/project/extra-projects/project/ExtraProjectPluginExample2.scala
@@ -5,7 +5,7 @@ object ExtraProjectPluginExample2 extends AutoPlugin {
   override def requires: Plugins = sbt.plugins.CorePlugin
   override def trigger = allRequirements
 
-  override def derivedProjects(proj: ProjectDefinition[_]): Seq[Project] =
+  override def derivedProjects(proj: ProjectDefinition[?]): Seq[Project] =
     // Make sure to exclude project extras to avoid recursive generation
     if (proj.projectOrigin != ProjectOrigin.DerivedProject) {
       val id = proj.id + "1"
diff --git a/sbt-app/src/sbt-test/project/sbt-plugin/src/main/scala/myplugin/MyPlugin.scala b/sbt-app/src/sbt-test/project/sbt-plugin/src/main/scala/myplugin/MyPlugin.scala
index f3439763e..354caf05a 100644
--- a/sbt-app/src/sbt-test/project/sbt-plugin/src/main/scala/myplugin/MyPlugin.scala
+++ b/sbt-app/src/sbt-test/project/sbt-plugin/src/main/scala/myplugin/MyPlugin.scala
@@ -8,7 +8,7 @@ case object MyPlugin extends AutoPlugin {
     val helloWorld = Def.taskKey[String]("log and return hello world")
   }
   import autoImport._
-  override def projectSettings: Seq[Def.Setting[_]] = Seq(
+  override def projectSettings: Seq[Def.Setting[?]] = Seq(
     // should not produce a "@nowarn annotation does not suppress any warnings" warning
     helloWorld := {
       streams.value.log("Hello world")
diff --git a/sbt-app/src/sbt-test/project/unique-settings-computation/project/A.scala b/sbt-app/src/sbt-test/project/unique-settings-computation/project/A.scala
index 118c7d1c8..46ac72ea4 100644
--- a/sbt-app/src/sbt-test/project/unique-settings-computation/project/A.scala
+++ b/sbt-app/src/sbt-test/project/unique-settings-computation/project/A.scala
@@ -8,11 +8,11 @@ object A extends AutoPlugin {
   import autoImport._
   override def trigger = allRequirements
 
-  override def buildSettings: Seq[Setting[_]] =
+  override def buildSettings: Seq[Setting[?]] =
     (foo := s"build ${buildCount.getAndIncrement}") ::
     Nil
 
-  override def globalSettings: Seq[Setting[_]] =
+  override def globalSettings: Seq[Setting[?]] =
     (foo := s"global ${globalCount.getAndIncrement}") ::
     (commands += setUpScripted) ::
     Nil
diff --git a/sbt-app/src/sbt-test/watch/overlapping/project/Stamps.scala b/sbt-app/src/sbt-test/watch/overlapping/project/Stamps.scala
index b8389d791..eb8de8b7c 100644
--- a/sbt-app/src/sbt-test/watch/overlapping/project/Stamps.scala
+++ b/sbt-app/src/sbt-test/watch/overlapping/project/Stamps.scala
@@ -5,7 +5,7 @@ import java.nio.file._
 import sbt.nio.Keys._
 
 object Stamps {
-  def check(key: TaskKey[_]): Def.Initialize[Task[Unit]] = Def.task {
+  def check(key: TaskKey[?]): Def.Initialize[Task[Unit]] = Def.task {
     (key / inputFileStamps).value.map {
       case (p, FileStamp.Hash(_)) =>
       case (p, _) =>