The following tests failed with NoRouteToHostException on some new Mac machines:
java/nio/channels/DatagramChannel/MulticastSendReceiveTests.java
java/nio/channels/DatagramChannel/AdaptorMulticasting.java
java/net/Socket/LinkLocal.java
java/net/MulticastSocket/SetOutgoingIf.java
java/net/MulticastSocket/Promiscuous.java
java/net/InetAddress/CheckJNI.java

We found there was a kind of coprocessor in the new Macs, the coprocessor is configured as a network interface but without route. So the tests always failed when they tried to send data from the network interface.

For example, the following log of MulticastSendReceiveTests.java:
----------System.out:(128/4775)----------

Test DatagramChannel to UNSPEC socket
join 225.4.5.6 @ en0
Send message from 10.133.68.130 -> group 225.4.5.6 (id=0x879910db)
Waiting to receive message
Received message from /10.133.68.130 (id=0x879910db)
Message expected
block 10.133.68.130
Exclude-mode filtering not supported!
join 225.4.5.6 @ en0 only-source 1.2.3.4
Include-mode filtering not supported!

Test DatagramChannel to INET socket
join 225.4.5.6 @ en0
Send message from 10.133.68.130 -> group 225.4.5.6 (id=0xff233b68)
Waiting to receive message
Received message from /10.133.68.130 (id=0xff233b68)
Message expected
block 10.133.68.130
Exclude-mode filtering not supported!
join 225.4.5.6 @ en0 only-source 1.2.3.4
Send message from 10.133.68.130 -> group 225.4.5.6 (id=0x822f5d01)
Waiting to receive message
No message received (correct)
join 225.4.5.6 @ en0 only-source 10.133.68.130
Send message from 10.133.68.130 -> group 225.4.5.6 (id=0xb70c0190)
Waiting to receive message
Received message from /10.133.68.130 (id=0xb70c0190)
Message expected

Test DatagramChannel to INET6 socket
join 225.4.5.6 @ en0
Send message from 10.133.68.130 -> group 225.4.5.6 (id=0xdb98b948)
Waiting to receive message
Received message from /10.133.68.130 (id=0xdb98b948)
Message expected
block 10.133.68.130
Exclude-mode filtering not supported!
join 225.4.5.6 @ en0 only-source 1.2.3.4
Include-mode filtering not supported!

Test DatagramChannel to UNSPEC socket
join 225.4.5.6 @ en1
Send message from 169.254.58.241 -> group 225.4.5.6 (id=0xa85c58b1)
Waiting to receive message
Received message from /169.254.58.241 (id=0xa85c58b1)
Message expected
block 169.254.58.241
Exclude-mode filtering not supported!
join 225.4.5.6 @ en1 only-source 1.2.3.4
Include-mode filtering not supported!

Test DatagramChannel to INET socket
join 225.4.5.6 @ en1
Send message from 169.254.58.241 -> group 225.4.5.6 (id=0x6d0c3714)
Waiting to receive message
Received message from /169.254.58.241 (id=0x6d0c3714)
Message expected
block 169.254.58.241
Exclude-mode filtering not supported!
join 225.4.5.6 @ en1 only-source 1.2.3.4
Send message from 169.254.58.241 -> group 225.4.5.6 (id=0x9a2a4472)
Waiting to receive message
No message received (correct)
join 225.4.5.6 @ en1 only-source 169.254.58.241
Send message from 169.254.58.241 -> group 225.4.5.6 (id=0x94ab1b2b)
Waiting to receive message
Received message from /169.254.58.241 (id=0x94ab1b2b)
Message expected

Test DatagramChannel to INET6 socket
join 225.4.5.6 @ en1
Send message from 169.254.58.241 -> group 225.4.5.6 (id=0x9aef40c5)
Waiting to receive message
Received message from /169.254.58.241 (id=0x9aef40c5)
Message expected
block 169.254.58.241
Exclude-mode filtering not supported!
join 225.4.5.6 @ en1 only-source 1.2.3.4
Include-mode filtering not supported!

Test DatagramChannel to UNSPEC socket
join ff02:0:0:0:0:0:0:a @ en0
Send message from fe80:0:0:0:c3a:428b:e19b:85ba%en0 -> group ff02:0:0:0:0:0:0:a (id=0xf063016a)
Waiting to receive message
Received message from /fe80:0:0:0:c3a:428b:e19b:85ba%4 (id=0xf063016a)
Message expected
block fe80:0:0:0:c3a:428b:e19b:85ba%en0
Exclude-mode filtering not supported!
join ff02:0:0:0:0:0:0:a @ en0 only-source fe80:0:0:0:0:0:0:1234
Include-mode filtering not supported!

Test DatagramChannel to INET6 socket
join ff02:0:0:0:0:0:0:a @ en0
Send message from fe80:0:0:0:c3a:428b:e19b:85ba%en0 -> group ff02:0:0:0:0:0:0:a (id=0x19797d9c)
Waiting to receive message
Received message from /fe80:0:0:0:c3a:428b:e19b:85ba%4 (id=0x19797d9c)
Message expected
block fe80:0:0:0:c3a:428b:e19b:85ba%en0
Exclude-mode filtering not supported!
join ff02:0:0:0:0:0:0:a @ en0 only-source fe80:0:0:0:0:0:0:1234
Include-mode filtering not supported!

Test DatagramChannel to UNSPEC socket
join ff02:0:0:0:0:0:0:a @ en1
Send message from fe80:0:0:0:10cf:f27d:b963:9b38%en1 -> group ff02:0:0:0:0:0:0:a (id=0x13faa23)
Waiting to receive message
Received message from /fe80:0:0:0:10cf:f27d:b963:9b38%7 (id=0x13faa23)
Message expected
block fe80:0:0:0:10cf:f27d:b963:9b38%en1
Exclude-mode filtering not supported!
join ff02:0:0:0:0:0:0:a @ en1 only-source fe80:0:0:0:0:0:0:1234
Include-mode filtering not supported!

Test DatagramChannel to INET6 socket
join ff02:0:0:0:0:0:0:a @ en1
Send message from fe80:0:0:0:10cf:f27d:b963:9b38%en1 -> group ff02:0:0:0:0:0:0:a (id=0xc1ee93e7)
Waiting to receive message
Received message from /fe80:0:0:0:10cf:f27d:b963:9b38%7 (id=0xc1ee93e7)
Message expected
block fe80:0:0:0:10cf:f27d:b963:9b38%en1
Exclude-mode filtering not supported!
join ff02:0:0:0:0:0:0:a @ en1 only-source fe80:0:0:0:0:0:0:1234
Include-mode filtering not supported!

Test DatagramChannel to UNSPEC socket
join ff02:0:0:0:0:0:0:a @ en6
Send message from fe80:0:0:0:aede:48ff:fe00:1122%en6 -> group ff02:0:0:0:0:0:0:a (id=0x2309ce22)
----------System.err:(18/1210)----------
java.net.NoRouteToHostException: No route to host
at java.base/sun.nio.ch.DatagramChannelImpl.send0(Native Method)
at java.base/sun.nio.ch.DatagramChannelImpl.sendFromNativeBuffer(DatagramChannelImpl.java:894)
at java.base/sun.nio.ch.DatagramChannelImpl.send(DatagramChannelImpl.java:871)
at java.base/sun.nio.ch.DatagramChannelImpl.send(DatagramChannelImpl.java:814)
at MulticastSendReceiveTests.sendDatagram(MulticastSendReceiveTests.java:79)
at MulticastSendReceiveTests.test(MulticastSendReceiveTests.java:184)
at MulticastSendReceiveTests.main(MulticastSendReceiveTests.java:276)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at com.sun.javatest.regtest.agent.MainActionHelper$AgentVMRunnable.run(MainActionHelper.java:298)
at java.base/java.lang.Thread.run(Thread.java:832)

JavaTest Message: Test threw exception: java.net.NoRouteToHostException
JavaTest Message: shutting down test

We searched the following information about the coprocessor:

The en6 interface is listed as iBridge according to system_profiler:

  iBridge:
      Type: USB
      BSD name: en6
      Kext name: AppleUSBNCM.kext
      Location: /System/Library/Extensions/AppleUSBNCM.kext
      Version: 5.0.0
      MAC Address: ac:de:48:00:11:22
      Product ID: 33331
      Vendor ID: 1452

"iBridge is the code name for the T series coprocessor (e.g. T1 or T2 chip) in newer Macs. It manages the Touch ID sensor, as well as the FaceTime camera and audio control. It is present even on Macs that don't have a Touch Bar, like the 2018 MacBook Air and Mac mini.”