ReadAheadIterator headOptionReverseCompatibility Altered To Final Val…

…ue Class

Utilizes value class to avoid allocating runtime objects unnecessarily, and is final so that the behavior cannot be overridden in subclasses

slick/src/main/scala/slick/util/ReadAheadIterator.scala

@@ -47,7 +47,7 @@ trait ReadAheadIterator[+T] extends BufferedIterator[T] {
 object ReadAheadIterator {
 
   /** Feature implemented in Scala library 2.12 this maintains functionality for 2.11 */
-  implicit class headOptionReverseCompatibility[T](readAheadIterator: ReadAheadIterator[T]){
+  final implicit class headOptionReverseCompatibility[T](val readAheadIterator: ReadAheadIterator[T]) extends AnyVal {
     def headOption : Option[T] = if (readAheadIterator.hasNext) Some(readAheadIterator.head) else None
   }
 }