add extra changes needed to get akka cluster support

cluster/src/main/scala/org/apache/pekko/cluster/ConfigUtil.scala

@@ -0,0 +1,54 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.pekko.cluster
+
+import com.typesafe.config.{ Config, ConfigValue, ConfigValueFactory, ConfigValueType }
+
+import scala.annotation.nowarn
+
+private[cluster] object ConfigUtil {
+
+  @nowarn("msg=deprecated")
+  def addAkkaConfig(cfg: Config, akkaVersion: String): Config = {
+    import scala.collection.JavaConverters._
+    val innerSet = cfg.entrySet().asScala
+      .filter(e => e.getKey.startsWith("pekko.") && e.getValue.valueType() != ConfigValueType.OBJECT)
+      .map { entry =>
+        entry.getKey.replace("pekko", "akka") -> adjustPackageNameIfNecessary(entry.getValue)
+      }
+    var newConfig = cfg
+    innerSet.foreach { case (key, value) =>
+      newConfig = newConfig.withValue(key, value)
+    }
+    newConfig.withValue("akka.version", ConfigValueFactory.fromAnyRef(akkaVersion))
+  }
+
+  private def adjustPackageNameIfNecessary(cv: ConfigValue): ConfigValue = {
+    if (cv.valueType() == ConfigValueType.STRING) {
+      val str = cv.unwrapped().toString
+      if (str.startsWith("org.apache.pekko")) {
+        ConfigValueFactory.fromAnyRef(str.replace("org.apache.pekko", "akka"))
+      } else {
+        cv
+      }
+    } else {
+      cv
+    }
+  }
+
+}

cluster/src/main/scala/org/apache/pekko/cluster/SeedNodeProcess.scala

@@ -47,6 +47,21 @@ private[cluster] abstract class SeedNodeProcess(joinConfigCompatChecker: JoinCon
     "Note that disabling it will allow the formation of a cluster with nodes having incompatible configuration settings. " +
     "This node will be shutdown!"
 
+  private lazy val needsAkkaConfig: Boolean = {
+    context.system.settings.config
+      .getStringList("pekko.remote.accept-protocol-names")
+      .contains("akka")
+  }
+
+  private lazy val akkaVersion: String = {
+    val cfg = context.system.settings.config
+    if (cfg.hasPath("akka.version")) {
+      cfg.getString("akka.version")
+    } else {
+      cfg.getString("pekko.cluster.akka.version")
+    }
+  }
+
   private def stopOrBecome(behavior: Option[Actor.Receive]): Unit =
     behavior match {
       case Some(done) => context.become(done) // JoinSeedNodeProcess
@@ -65,8 +80,12 @@ private[cluster] abstract class SeedNodeProcess(joinConfigCompatChecker: JoinCon
     val configToValidate =
       JoinConfigCompatChecker.filterWithKeys(requiredNonSensitiveKeys, context.system.settings.config)
 
+    val adjustedConfig = if (needsAkkaConfig)
+      ConfigUtil.addAkkaConfig(configToValidate, akkaVersion)
+    else configToValidate
+
     seedNodes.foreach { a =>
-      context.actorSelection(context.parent.path.toStringWithAddress(a)) ! InitJoin(configToValidate)
+      context.actorSelection(context.parent.path.toStringWithAddress(a)) ! InitJoin(adjustedConfig)
     }
   }