make NonEmptyChainImpl

core/src/main/scala/cats/data/NonEmptyChain.scala

@@ -22,14 +22,15 @@
 package cats
 package data
 
-import NonEmptyChainImpl.create
-
 import cats.instances.StaticMethods
 import cats.kernel._
 
 import scala.collection.immutable.SortedMap
 
-private[data] object NonEmptyChainImpl extends NonEmptyChainInstances with ScalaVersionSpecificNonEmptyChainImpl {
+// For internal purposes only - do not use!
+// This object is kept public for the sake of binary compatibility.
+// The visibility can be changed in future versions.
+object NonEmptyChainImpl extends NonEmptyChainInstances with ScalaVersionSpecificNonEmptyChainImpl {
   // The following 3 types are components of a technique to
   // create a no-boxing newtype. It's copied from the
   // newtypes lib by @alexknvl
@@ -83,10 +84,12 @@ class NonEmptyChainOps[A](private val value: NonEmptyChain[A])
     extends AnyVal
     with NonEmptyCollection[A, Chain, NonEmptyChain] {
 
+  import NonEmptyChainImpl.{create, unwrap}
+
   /**
    * Converts this chain to a `Chain`
    */
-  final def toChain: Chain[A] = NonEmptyChainImpl.unwrap(value)
+  final def toChain: Chain[A] = unwrap(value)
 
   /**
    * Returns a new NonEmptyChain consisting of `a` followed by this. O(1) runtime.