What are the different types of transaction propagation mechanisms in Spring?

In the Spring framework, there are several types of transaction propagation mechanisms.

1. By default, add to the current transaction if one exists or create a new transaction if none exists.
2. SUPPORTS: If there is currently a transaction, join it; if there is no transaction currently, run in a non-transactional manner.
3. It is required to join the transaction if one currently exists, and to throw an exception if there is no transaction present.
4. REQUIRES_NEW: Creates a new transaction, suspends the current transaction if it exists.
5. NOT_SUPPORTED: Execute in a non-transactional manner, suspending the current transaction if one exists.
6. NEVER: Perform in a non-transactional manner, throwing an exception if a transaction is currently in progress.
7. If there is already a transaction in progress, the code will execute in a nested transaction; otherwise, a new nested transaction will be created.