do not warn for explicitely overriden stringPrefix

Author: hamzaremmal

library/src/scala/collection/mutable/ListMap.scala

@@ -15,7 +15,7 @@ package mutable
 
 import scala.language.`2.13`
 import language.experimental.captureChecking
-import scala.annotation.tailrec
+import scala.annotation.{tailrec, nowarn}
 import scala.collection.generic.DefaultSerializable
 import scala.collection.immutable.List
 
@@ -68,6 +68,7 @@ class ListMap[K, V]
   final override def size: Int = siz
   override def knownSize: Int = size
   override def isEmpty: Boolean = size == 0
+  @nowarn("""cat=deprecation&origin=scala\.collection\.Iterable\.stringPrefix""")
   override protected def stringPrefix = "ListMap"
 }
 

library/src/scala/collection/mutable/OpenHashMap.scala

@@ -15,6 +15,8 @@ package mutable
 
 import scala.language.`2.13`
 import language.experimental.captureChecking
+
+import scala.annotation.nowarn
 import java.lang.Integer.numberOfLeadingZeros
 import java.util.ConcurrentModificationException
 import scala.collection.generic.DefaultSerializable
@@ -304,5 +306,6 @@ class OpenHashMap[Key, Value](initialSize : Int)
     this
   }
 
+  @nowarn("""cat=deprecation&origin=scala\.collection\.Iterable\.stringPrefix""")
   override protected def stringPrefix = "OpenHashMap"
 }