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1. Modules are not part of the JSON plan. They must have been loaded as before.
2. Most of the table/session configuration is not part of the JSON plan. It must be the same as before. This is important for table factories and UDFs where we don't know what they have consumed.
3. Configuration consumed by ExecNode should be persisted if it influences the topology or has runtime implications (i.e. not just forwarding the value but using it for calculation). (e.g. `table.exec.sink.not-null-enforcer`). In other words: it is not necessary to persist code gen options but we should persist `table.exec.` options.
4. Temporary DDL statements (to init the table environment and then make sure the temporary UDFs and connectors can be found) are not part of the JSON plan.
5. We do not version types. We assume that the type system is stable or will only be extended by more types but not modified.
6. The origin of every catalog object is stored with the object identifier in the JSON plan. However, we cannot assume that all catalog metadata stays constant as a catalog might be shared across teams. We can only assume that the catalog instance and type (e.g. Hive catalog) stays constant for a session to provide a table factory.
7. The JSON plan contains no implementation details (i.e. no classes) and is fully declarative.
8. The JSON plan is versioned by Flink version. 
9. The JSON plan is internal to Flink. We don't support external changes to the plan officially. However, the JSON plan format must not change between patch releases.
10. Flink will not perform any kind of validation or consistency checks during restore except for the supported Flink plan version.
11. We do not version connectors and formats. If a connector adds a new ability, we can simply not apply this ability for older plans. Removing an ability is a problem and would require a correcting operator afterwards.

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Remark to 10: In other words: We verify whether the supported Flink version contained in the plan but is supported. This must not necessarily be the last Flink version. But after that the only consistency check will be the restore deserialization itself.

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