Using AWS SDK 1.6.0.1 in a particular Vpc using instances, each with one attached ENI.

At approximately 12:00 UTC on Sunday 13 October, I saw two changes in the behaviour of requests to AmazonWebServices.

Change #1.
For as long as I can remember, GET http://169.254.169.254/latest/meta-data/public-ipv4 has returned a 404. I have never been clear on why this happened, because the actual behaviour seems to disagree with the doc at http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AESDG-chapter-instancedata.html.
Nevertheless until 12:00 UTC yesterday GET http://169.254.169.254/latest/meta-data/local-ipv4 returned the IP address of the latest NIC to be attached. In the usual case, this will be at device 1 whenever an ENI is attached. Therefore, GET http://169.254.169.254/latest/meta-data/local-ipv4 returned the public IP address whenever I ran it prior to 12:00 UTC yesterday. I found this useful, even though it seems to disagree with the doc yet again. But after 12:00 UTC it returns the internal IP address, so reversing this previous feature.
There no longer appears to be a viable way of discovering the public IP address from the hypervisor.

Change #2.
The response to the getAssociation() method of NetworkInterface does not seem to be the same as in previous runs for all week. Previously the following code returned a non-empy association when passed in the instanceId of an instance with an attached ENI which had an EIP associated to it.

Here is a code fragment. The final entry now returns null.

public void assocTest() {
List listOfInstanceId = Arrays.asList(instanceId);
DescribeNetworkInterfacesRequest networkInterfacesRequest = new DescribeNetworkInterfacesRequest()
.withFilters(new Filter("attachment.instance-id", listOfInstanceId));
List networkInterfaces = ec2.describeNetworkInterfaces(networkInterfacesRequest)
.getNetworkInterfaces();
if (networkInterfaces.size() > 0) {
NetworkInterface networkInterface = networkInterfaces.get(0);
NetworkInterfaceAttachment networkInterfaceAttachment = networkInterface.getAttachment();
NetworkInterfaceAssociation networkInterfaceAssociation = networkInterface.getAssociation();
System.out.println("networkInterface " + networkInterface);
System.out.println("networkInterfaceAttachment " + networkInterfaceAttachment);
System.out.println("networkInterfaceAssociation " + networkInterfaceAssociation);
}
}

Although this behaviour seems to have changed, the result on the commandline of ec2din $instanceId still returns a NICASSOCIATION with the public IP.

Please help explain what has changed. Why is a valid NetworkInterfaceAssociation object no longer returned?