Support Scala 3

build.sbt

@@ -1,14 +1,15 @@
 import ReleaseTransformations._
+import Dependencies._
 
 lazy val baseSettings = Seq(
   scalaVersion := "2.13.10",
-  crossScalaVersions := Seq(scalaVersion.value),
+  crossScalaVersions := Seq(scalaVersion.value, "3.2.1"),
   organization := "com.madgag.scala-git",
   scmInfo := Some(ScmInfo(
     url("https://github.com/rtyley/scala-git"),
     "scm:git:git@github.com:rtyley/scala-git.git"
   )),
-  licenses := Seq("Apache-2.0" -> url("http://www.apache.org/licenses/LICENSE-2.0")),
+  licenses := Seq("Apache-2.0" -> url("https://www.apache.org/licenses/LICENSE-2.0")),
   scalacOptions ++= Seq("-deprecation", "-unchecked")
 )
 

scala-git/src/main/scala/com/madgag/diff/MapDiff.scala

@@ -1,6 +1,6 @@
 package com.madgag.diff
 
-import com.madgag.scala.collection.decorators.MapDecorator
+import com.madgag.scala.collection.decorators._
 
 object MapDiff {
   def apply[K,V](before: Map[K,V], after: Map[K,V]): MapDiff[K,V] =
@@ -20,6 +20,6 @@ case class MapDiff[K, V](beforeAndAfter: Map[BeforeAndAfter, Map[K,V]]) {
   lazy val unchangedMap: Map[K,V] = beforeAndAfter(Before).view.filterKeys(unchanged).toMap
 
   lazy val changedMap: Map[K,Map[BeforeAndAfter, V]] =
-    changed.map(k => k -> beforeAndAfter.mapV(_(k)).toMap).toMap
+    changed.map(k => k -> beforeAndAfter.mapV(_(k))).toMap
 
 }

scala-git/src/main/scala/com/madgag/git/package.scala

@@ -39,9 +39,6 @@ import org.eclipse.jgit.treewalk.TreeWalk
 import org.eclipse.jgit.treewalk.filter.{AndTreeFilter, TreeFilter}
 import org.eclipse.jgit.util.FS
 
-
-
-
 package object git {
 
   implicit class RichByteArray(bytes: Array[Byte]) {
@@ -94,7 +91,7 @@ package object git {
       (revWalk, revWalk.getObjectReader)
     }
 
-    def nonSymbolicRefs = repo.getAllRefs.asScala.values.filterNot(_.isSymbolic)
+    def nonSymbolicRefs: Iterable[Ref] = repo.getRefDatabase.getRefs.asScala.toSeq.filterNot(_.isSymbolic)
 
   }
 
@@ -172,7 +169,7 @@ package object git {
   implicit class RichRevObject(revObject: RevObject) {
     lazy val typeString = Constants.typeString(revObject.getType)
 
-    def toTree(implicit revWalk: RevWalk): Option[RevTree] = treeOrBlobPointedToBy(revObject).right.toOption
+    def toTree(implicit revWalk: RevWalk): Option[RevTree] = treeOrBlobPointedToBy(revObject).toOption
   }
 
   val FileModeNames = Map(