The idea is for a filter plugin that can be used to simplify migrations, In some ways, the suggested filter could probably also be implemented as a number of regex filters, but that would possibly require a large number of different filters and some rather complex pattern matching. The idea here is to replace, typically in an SQL statement, some Oracle specific SQL with MariaDB friendly SQL. This is sometimes useful even in production, but probably even more so when testing, migrating or running a POC.
Examples features would be (for an Oracle migration filter):

• Map DECODE to CASE statements
• Map SYSDATE to NOW()
• Oracle outer join (using ) to ANSI-style OUTER JOIN
• Quoted identifiers to backticks
• Map || to CONCAT for concatenation