JIRA: https://jira.spring.io/browse/INT-3474
When the MethodInvokingMessageHandler skips ineligible methods while
searching it emits a stack trace under DEBUG logging. This is not
needed, a simple log message is enough to convey the information.
Some POJOs gain ineligible methods when wrapped in a proxy so this
is no fault of the developer.
Other reasons for skipping methods (improperly set annotations etc)
continue to emit a stack trace.
INT-3474: Polishing
Rethrow `IneligibleMethodException` as `IllegalArgumentException` in case of a single `method` for processor
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