DirectByteBufferPool calls DirectByteBuffer#clean twice

[johanandren]

DirectByteBuffer#clean() was called twice. (via reflection)
https://github.com/openjdk-mirror/jdk7u-jdk/blob/jdk7u6-b08/src/share/classes/java/nio/Direct-X-Buffer.java.template#L103

Cleaner#clean method was fetched but not called.
https://github.com/openjdk-mirror/jdk7u-jdk/blob/jdk7u6-b08/src/share/classes/sun/misc/Cleaner.java#L138

invoke cleaner method to Clean throws IllegalArgumentException

repl-example

scala> val cleanerMethod = Class.forName("java.nio.DirectByteBuffer").getMethod("cleane
cleanerMethod: java.lang.reflect.Method = public sun.misc.Cleaner java.nio.DirectByteBu

scala> cleanerMethod.setAccessible(true)

scala> val cleanMethod = Class.forName("sun.misc.Cleaner").getMethod("clean")
cleanMethod: java.lang.reflect.Method = public void sun.misc.Cleaner.clean()

scala> cleanMethod.setAccessible(true)

scala> val bb = java.nio.ByteBuffer.allocateDirect(1000)
bb: java.nio.ByteBuffer = java.nio.DirectByteBuffer[pos=0 lim=1000 cap=1000]

scala> bb.isDirect
res2: Boolean = true

scala> val cleaner = cleanerMethod.invoke(bb)
cleaner: Object = sun.misc.Cleaner@79a7bfbc

scala> cleanerMethod.invoke(cleaner)
java.lang.IllegalArgumentException: object is not an instance of declaring class
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:
  at java.lang.reflect.Method.invoke(Method.java:498)
  ... 32 elided

scala> cleanMethod.invoke(cleaner)
res4: Object = null