[BUG] Jackson Deserializer for java.time types isn't RFC3339 compliant

[beikov]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
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• Have you tested with the latest master to confirm the issue still exists?
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Description

When parsing a java.time type with Jackson and the value is not in ISO8601 format (which is a subset of RFC3339), a parsing error occurs. The Jackson configuration in generated projects misses certain aspects.

openapi-generator version

7.10-SNAPSHOT

Suggest a fix

See #19925