-Xsource:3

appender/src/main/scala/io/github/nafg/cloudlogging/appender/CloudJsonLoggingAppender.scala

@@ -5,7 +5,7 @@ import ch.qos.logback.classic.spi.{ILoggingEvent, IThrowableProxy, ThrowableProx
 import com.google.cloud.logging.HttpRequest.RequestMethod
 import com.google.cloud.logging.Logging.WriteOption
 import com.google.cloud.logging.logback.LoggingAppender
-import com.google.cloud.logging.{Option => _, _}
+import com.google.cloud.logging.{Option as _, *}
 import io.circe.{Json, JsonNumber, JsonObject}
 import io.github.nafg.cloudlogging.marker.JsonMarker
 import org.slf4j.Marker
@@ -16,7 +16,7 @@ import java.time.Instant
 import java.util
 import java.util.Collections
 import scala.collection.mutable
-import scala.jdk.CollectionConverters._
+import scala.jdk.CollectionConverters.*
 
 object CloudJsonLoggingAppender {
   private def severityFor(level: Level) =
@@ -215,6 +215,6 @@ class CloudJsonLoggingAppender extends LoggingAppender {
 
   override def append(e: ILoggingEvent): Unit = {
     val logEntry = CloudJsonLoggingAppender.logEntryFor(e)
-    logging.write(Collections.singleton(logEntry), defaultWriteOptions: _*)
+    logging.write(Collections.singleton(logEntry), defaultWriteOptions*)
   }
 }

appender/src/test/scala/io/github/nafg/cloudlogging/appender/CloudJsonLoggingAppenderTests.scala

@@ -1,19 +1,17 @@
 package io.github.nafg.cloudlogging.appender
 
-import java.util
-
-import scala.jdk.CollectionConverters._
-
-import io.github.nafg.cloudlogging.marker.JsonMarker
-
-import ch.qos.logback.classic.spi._
+import ch.qos.logback.classic.spi.*
 import ch.qos.logback.classic.{Level, LoggerContext}
 import com.google.cloud.logging.{Payload, Severity}
 import io.circe.Json
-import org.scalatest.Inside._
+import io.github.nafg.cloudlogging.marker.JsonMarker
+import org.scalatest.Inside.*
 import org.scalatest.funsuite.AnyFunSuite
 import org.slf4j.Marker
 
+import java.util
+import scala.jdk.CollectionConverters.*
+
 class CloudJsonLoggingAppenderTests extends AnyFunSuite {
   test("Exception") {
     val loggingEvent: ILoggingEvent = new ILoggingEvent {
@@ -49,11 +47,11 @@ class CloudJsonLoggingAppenderTests extends AnyFunSuite {
       assert(message.startsWith(loggingEvent.getMessage))
     }
 
-    inside(data.get("marker")) { case marker: util.Map[_, _] =>
+    inside(data.get("marker")) { case marker: util.Map[String, String] =>
       assert(marker.get("name") == "testMarker")
     }
 
-    inside(data.get("throwable")) { case throwable: util.Map[_, _] =>
+    inside(data.get("throwable")) { case throwable: util.Map[String, String] =>
       assert(throwable.get("message") == "Some error")
       assert(throwable.containsKey("stack"))
     }

build.sbt

@@ -10,12 +10,19 @@ mergifyExtraConditions := Seq(
     (Attr.Author :== "nafg-scala-steward[bot]")
 )
 
-val noFatalWarnings = scalacOptions -= "-Xfatal-warnings"
+val adjustScalacOptions = Seq(
+  scalacOptions -= "-Xfatal-warnings",
+  scalacOptions ++=
+    (if (scalaVersion.value.startsWith("3."))
+       Nil
+     else
+       Seq("-Xsource:3"))
+)
 
 lazy val marker =
   project
     .settings(
-      noFatalWarnings,
+      adjustScalacOptions,
       libraryDependencies += "io.circe" %% "circe-core" % "0.14.5",
       libraryDependencies += "org.slf4j" % "slf4j-api"  % "2.0.7"
     )
@@ -24,7 +31,7 @@ lazy val appender =
   project
     .dependsOn(marker)
     .settings(
-      noFatalWarnings,
+      adjustScalacOptions,
       libraryDependencies += "com.google.cloud" % "google-cloud-logging-logback" % "0.130.21-alpha",
       libraryDependencies += "org.scalatest"   %% "scalatest"                    % "3.2.16" % Test
     )