Use some magic for cross publishing

src/main/scala/de/zalando/beard/parser/BeardTemplateListener.scala

@@ -4,7 +4,7 @@ import de.zalando.beard.BeardParser._
 import de.zalando.beard.BeardParserBaseListener
 import de.zalando.beard.ast._
 import scala.collection.immutable.Seq
-import scala.jdk.CollectionConverters._
+import de.zalando.beard.parser.JDKCollectionConvertersCompat.Converters._
 
 class BeardTemplateListener extends BeardParserBaseListener {
 

src/main/scala/de/zalando/beard/parser/JDKCollectionConvertersCompat.scala

@@ -0,0 +1,26 @@
+package de.zalando.beard.parser
+
+/**
+ * Magic to get cross-compiling access to `scala.jdk.CollectionConverters`
+ *  with a fallback on `scala.collection.JavaConverters`, without deprecation
+ *  warning in any Scala version.
+ */
+object JDKCollectionConvertersCompat {
+  object Scope1 {
+    object jdk {
+      type CollectionConverters = Int
+    }
+  }
+  import Scope1._
+
+  object Scope2 {
+    import scala.collection.{JavaConverters => CollectionConverters}
+    object Inner {
+      import scala._
+      import jdk.CollectionConverters
+      val Converters = CollectionConverters
+    }
+  }
+
+  val Converters = Scope2.Inner.Converters
+}