GET /_migration/deprecations doesn't report node deprecations if low watermark exceeded #137004
Description
This seemingly-innocuous code ...
... doesn't work because issues came from Stream#toList and is therefore immutable. Instead it throws a UOE:
java.lang.UnsupportedOperationException: null
at java.util.ImmutableCollections.uoe(ImmutableCollections.java:159) ~[?:?]
at java.util.ImmutableCollections$AbstractImmutableCollection.add(ImmutableCollections.java:164) ~[?:?]
at org.elasticsearch.xpack.deprecation.TransportNodeDeprecationCheckAction.nodeOperation(TransportNodeDeprecationCheckAction.java:146) ~[?:?]
at org.elasticsearch.xpack.deprecation.TransportNodeDeprecationCheckAction.nodeOperation(TransportNodeDeprecationCheckAction.java:110) ~[?:?]
at org.elasticsearch.xpack.deprecation.TransportNodeDeprecationCheckAction.nodeOperation(TransportNodeDeprecationCheckAction.java:43) ~[?:?]
at org.elasticsearch.action.support.nodes.TransportNodesAction.nodeOperationAsync(TransportNodesAction.java:261) ~[elasticsearch-8.19.5.jar:?]
at org.elasticsearch.action.support.nodes.TransportNodesAction$NodeTransportHandler.lambda$messageReceived$0(TransportNodesAction.java:277) ~[elasticsearch-8.19.5.jar:?]
at org.elasticsearch.action.ActionListener.run(ActionListener.java:454) ~[elasticsearch-8.19.5.jar:?]
at org.elasticsearch.action.support.nodes.TransportNodesAction$NodeTransportHandler.messageReceived(TransportNodesAction.java:275) ~[elasticsearch-8.19.5.jar:?]
at org.elasticsearch.transport.RequestHandlerRegistry.processMessageReceived(RequestHandlerRegistry.java:86) ~[elasticsearch-8.19.5.jar:?]
at org.elasticsearch.transport.TransportService$6.doRun(TransportService.java:1078) ~[elasticsearch-8.19.5.jar:?]
at org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingAbstractRunnable.doRun(ThreadContext.java:1044) ~[elasticsearch-8.19.5.jar:?]
at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:27) ~[elasticsearch-8.19.5.jar:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1090) ~[?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:614) ~[?:?]
at java.lang.Thread.run(Thread.java:1474) ~[?:?]
Such node-level failures do not propagate back to the API response, they're just logged and then silently dropped here:
This sort of node-level failure is more likely than you might think because we report low watermark violations far too liberally.