What practice does MuleSoft recommend for custom Java transformations?

• A. Encapsulate them in Java classes
• B. Implement all logic in DataWeave only
• C. Avoid using Java entirely
• D. Write Java code inline in flows

Answer: (A)

Encapsulating custom Java transformations in dedicated Java classes keeps the flow clean and makes the logic reusable and testable. By isolating Java code in its own class, you can unit test the transformation without running the entire Mule application, reuse the same logic across multiple flows, and update or replace it without touching the flow structure. DataWeave handles most straightforward mappings, but when you need complex algorithms or strongly typed logic, putting that Java code in a separate class and invoking it from the flow is the more maintainable approach. Writing Java inline in a flow or scattering Java across the project makes testing harder and reduces readability, so the recommended pattern is to place Java in its own class and call it as needed.