🧩 Your MapStruct Mappers Are Hiding Null Bugs

MapStruct is a common Java mapping library, but its default configuration often hides null bugs. When a target field lacks a matching source, the unmappedTargetPolicy defaults to WARN, allowing code to compile and pass tests despite missing mappings. This leads to unexpected null values in production. To ensure mappers are safe, testable, and predictable, developers should configure the compiler to fail on missing mappings instead of merely issuing a warning during the annotation processing phase.