Scott Fredrickson developed support for the Groovy !in operator in the openrewrite/rewrite repository, enhancing the Rewrite Java Library’s ability to parse and preserve this syntax within the Gradle Groovy DSL. He updated the Groovy parser visitor and printer using Java and Groovy, ensuring that code using the !in operator is correctly interpreted and rewritten. To validate the implementation, Scott created comprehensive end-to-end tests, strengthening regression safety and test coverage for Groovy DSL parsing. His work focused on parser development and Java-based tooling, addressing a nuanced language feature and improving the reliability of automated code transformations in the Rewrite ecosystem.