Provide ThreadLocalRandom wrapper only on JDK8 as it is buggy in JDK7

libraries/stdlib/jdk8/src/kotlin/internal/jdk8/JDK8PlatformImplementations.kt

@@ -21,6 +21,8 @@ import java.util.regex.MatchResult
 import java.util.regex.Matcher
 import kotlin.internal.PlatformImplementations
 import kotlin.internal.jdk7.JDK7PlatformImplementations
+import kotlin.random.Random
+import kotlin.random.jdk8.PlatformThreadLocalRandom
 
 internal open class JDK8PlatformImplementations : JDK7PlatformImplementations() {
 
@@ -34,4 +36,6 @@ internal open class JDK8PlatformImplementations : JDK7PlatformImplementations()
             null
     }
 
+    override fun defaultPlatformRandom(): Random = PlatformThreadLocalRandom()
+
 }

libraries/stdlib/jdk8/src/kotlin/random/jdk8/PlatformThreadLocalRandom.kt

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package kotlin.random.jdk8
+
+import java.util.concurrent.ThreadLocalRandom
+
+@Suppress("INVISIBLE_REFERENCE", "INVISIBLE_MEMBER", "CANNOT_OVERRIDE_INVISIBLE_MEMBER")
+internal class PlatformThreadLocalRandom : kotlin.random.AbstractPlatformRandom() {
+    // TODO no bridge generated for covariant override
+    override val impl: java.util.Random get() = ThreadLocalRandom.current()
+
+    override fun nextInt(origin: Int, bound: Int): Int = ThreadLocalRandom.current().nextInt(origin, bound)
+    override fun nextLong(bound: Long): Long = ThreadLocalRandom.current().nextLong(bound)
+    override fun nextLong(origin: Long, bound: Long): Long = ThreadLocalRandom.current().nextLong(origin, bound)
+    override fun nextDouble(bound: Double): Double = ThreadLocalRandom.current().nextDouble(bound)
+    override fun nextDouble(origin: Double, bound: Double): Double = ThreadLocalRandom.current().nextDouble(origin, bound)
+}