Place a .prettierrc in your workspace.
(Or alternatively an appropriate .editorconfig.)
Changes require restart to take effect.
Summary of deploy process
npm i -g vsce
vsce package
vsce publish
Acknowledgments
This plugin is based on mwpb.java-prettier-formatter. We updated the underlying tools, updated all dependencies to their latest compatible versions, updated the VSCode plugin module, and converted the project to TypeScript. Big thanks to them and and the projects below!