This modifies xcontent serialization of Exceptions to contain suppressed
exceptions. If there are any suppressed exceptions they are included in
the exception response by default. The reasoning here is that they are
fairly rare but when they exist they almost always add extra useful
information. Take, for example, the response when you specify two broken
ingest pipelines:
```
{
"error" : {
"root_cause" : ...snip...
"type" : "parse_exception",
"reason" : "[field] required property is missing",
"header" : {
"processor_type" : "set",
"property_name" : "field"
},
"suppressed" : [
{
"type" : "parse_exception",
"reason" : "[field] required property is missing",
"header" : {
"processor_type" : "convert",
"property_name" : "field"
}
}
]
},
"status" : 400
}
```
Moreover, when suppressed exceptions come from 500 level errors should
give us more useful debugging information.
Closes#23392
The rejected execution handler API says that rejectedExecution(Runnable,
ThreadPoolExecutor) throws a RejectedExecutionException if the task must
be rejected due to capacity on the executor. We do throw something that
smells like a RejectedExecutionException (it is named
EsRejectedExecutionException) yet we violate the API because
EsRejectedExecutionException is not a RejectedExecutionException. This
has caused problems before where we try to catch RejectedExecution when
invoking rejectedExecution but this causes EsRejectedExecutionException
to go uncaught. This commit addresses this by modifying
EsRejectedExecutionException to extend
RejectedExecutionException.
* Factor UnknownNamedObjectException into its own class
This moves the inner class `UnknownNamedObjectException` from
`NamedXContentRegistry` into a top-level class. This is so that
`NamedXContentRegistry` doesn't have to depend on StreamInput and StreamOutput.
Relates to #28504
