FlowScriptFlowScript is the expression language used inside FlowSetu transform steps. It exists to reshape data — reading and writing JSON, parsing and emitting CSV, manipulating strings and dates, arithmetic, and type conversion — without writing a Java class for every intermediate structure.Where expressions runExpressions are evaluated against the message passing through the flow, and compile into the generated Java rather than being interpreted by a runtime of ours. There is nothing extra to install in the exported project.Reading configurationUse $p("key") to read a configuration property. The value comes from the active environment's properties file at startup, so the same expression resolves differently in dev and prod without the flow changing.Coming from DataWeaveStraightforward field mapping, renaming and simple transforms translate closely. Multi-input joins, recursive functions and heavy reliance on DataWeave's implicit type coercion are where a migration needs a developer's judgement rather than a mechanical conversion.See the syntax reference and recipes for the full function list and worked examples.