Fix JsonMemoryFootprintSpec on JDK 21 / Scala 3

(cherry picked from commit de19226)

play-json/jvm/src/test/scala-3/play/api/libs/json/JsonMemoryFootprintSpec.scala

@@ -6,14 +6,15 @@ package play.api.libs.json
 
 import org.openjdk.jol.info.GraphLayout
 import org.scalatest.freespec.AnyFreeSpec
+import scala.util.Properties
 import scala.util.chaining._
 
 class JsonMemoryFootprintSpec extends AnyFreeSpec {
 
   "Json.parse" - {
     "obj0" in assertSizes("""{}""", 16, 16)
-    "obj1" in assertSizes("""{"1":true}""", 152, 168)
-    "obj4" in assertSizes("""{"1":true,"2":true,"3":true,"4":true}""", 296, 312)
+    "obj1" in assertSizes("""{"1":true}""", 152, 168, expectedJdk21 = Some(160),  hashedJdk21 = Some(184))
+    "obj4" in assertSizes("""{"1":true,"2":true,"3":true,"4":true}""", 296, 312, expectedJdk21 = Some(304),  hashedJdk21 = Some(328))
 
     "arr0" in assertSizes("""[]""", 40, 40)
     "arr1" in assertSizes("""[true]""", 120, 120)
@@ -33,38 +34,39 @@ class JsonMemoryFootprintSpec extends AnyFreeSpec {
   "JsObject" - {
     def obj(json: String) = Json.parse(json).as[JsObject]
     "obj0 ++ obj0" in assertSize(obj("{}") ++ obj("{}"), 16)
-    "obj0 ++ obj1" in assertSize(obj("{}") ++ obj("""{"1":true}"""), 152)
-    "obj1 ++ obj0" in assertSize(obj("""{"1":true}""") ++ obj("""{}"""), 152)
+    "obj0 ++ obj1" in assertSize(obj("{}") ++ obj("""{"1":true}"""), 152, expectedJdk21 = Some(160))
+    "obj1 ++ obj0" in assertSize(obj("""{"1":true}""") ++ obj("""{}"""), 152, expectedJdk21 = Some(160))
 
-    "obj1.value" in assertSize(obj("""{"1":true}""").tap(_.value), 152)
+    "obj1.value" in assertSize(obj("""{"1":true}""").tap(_.value), 152, expectedJdk21 = Some(160))
   }
 
   "malicious" - {
     // if we pack data into ~1KB of input, how much memory amplification can we achieve?
     def arr1KB(elem: String, targetSize: Int = 1000): String =
       Iterator.continually(elem).take(targetSize / (elem.length + 1)).mkString("[", ",", "]")
     "obj0" in assertSizes(arr1KB("{}"), 7432, 7432)
-    "obj1" in assertSizes(arr1KB("""{"a":6}"""), 29568, 31568)
+    "obj1" in assertSizes(arr1KB("""{"a":6}"""), 29568, 31568, expectedJdk21 = Some(30568),  hashedJdk21 = Some(33568))
     "nums" in assertSizes(arr1KB("6"), 42104, 42104)
     "arr0" in assertSizes(arr1KB("[]"), 15424, 15424)
     "arr1" in assertSizes(arr1KB("[6]"), 51080, 51080)
   }
 
-  private def assertSizes(input: String, expected: Long, hashed: Long) = {
-    assertSize(Json.parse(input), expected)
+  private def assertSizes(input: String, expected: Long, hashed: Long, expectedJdk21: Option[Long] = None, hashedJdk21: Option[Long] = None) = {
+    assertSize(Json.parse(input), expected, expectedJdk21)
     withClue("After hashCode():")(
       assertSize(
         {
           val t = Json.parse(input)
           t.hashCode()
           t
         },
-        hashed
+        hashed,
+        hashedJdk21
       )
     )
   }
 
-  private def assertSize(a: => JsValue, expected: Long) = {
+  private def assertSize(a: => JsValue, expected: Long, expectedJdk21: Option[Long] = None) = {
     val layout1  = GraphLayout.parseInstance(a)
     val layout2  = GraphLayout.parseInstance(a)
     val distinct = layout1.subtract(layout2) // shared singletons don't count.
@@ -74,7 +76,7 @@ class JsonMemoryFootprintSpec extends AnyFreeSpec {
          |${distinct.toPrintable}""".stripMargin
 
     withClue(clue) {
-      assert(distinct.totalSize() === expected)
+      assert(distinct.totalSize() === expectedJdk21.filter(_ => Properties.isJavaAtLeast("21")).getOrElse(expected))
     }
   }
 }