[Java] MemoryUtil.directBuffer throws UnsupportedOperationException on Java 21

[pburka]

Describe the bug, including details regarding any error messages, version, and platform.

On an early access build of Java 21, I'm seeing some failures in Apache Arrow tests. The same tests work on Java 17, 18, 19 and 20.

Test failures all look like this:

java.lang.UnsupportedOperationException: sun.misc.Unsafe or java.nio.DirectByteBuffer.<init>(long, int) not available
       org.apache.arrow.memory.util.MemoryUtil.directBuffer(MemoryUtil.java:167)
       org.apache.arrow.memory.ArrowBuf.getDirectBuffer(ArrowBuf.java:228)
       org.apache.arrow.memory.ArrowBuf.nioBuffer(ArrowBuf.java:223)
       org.apache.arrow.vector.ipc.ReadChannel.readFully(ReadChannel.java:87)
       org.apache.arrow.vector.ipc.message.MessageSerializer.readMessageBody(MessageSerializer.java:727)
       org.apache.arrow.vector.ipc.message.MessageChannelReader.readNext(MessageChannelReader.java:67)
       org.apache.arrow.vector.ipc.ArrowStreamReader.loadNextBatch(ArrowStreamReader.java:145)

From a brief investigation, it looks like the private (long, int) constructor has been replaced with a (long, long) constructor in Java 21. (See https://github.com/openjdk/jdk/blob/42fa000a7d042e425913aab2842f8166a0c2172a/src/java.base/share/classes/java/nio/Direct-X-Buffer.java.template#L180-L188 and openjdk/jdk@a56598f)

Component(s)

Java

[lidavidm]

CC @davisusanibar

[dongjoon-hyun]

Hi, All. I made a PR for this issue.