8ee2d4e0_kasper_s_source__What_
[How?] Since the API is designed for Convention-over-Configuration, putting a plain String property as the groovy code was maybe a bit naive. There are two strategies to pursue if you have properties which need special rendering on the UI: Provide more metadata about the property (Quite easy), or build your own renderer for it (most flexible, but also more complex). In this case I was able to simply provide more metadata, using the @StringProperty annotation: @Configured @StringProperty(multiline = true, mimeType = "text/groovy") String code The default DataCleaner string property widget will then provide a multi-line text field with syntax coloring for the specific mime-type: [What?] 
The 'Code' text field was a single line field and did not look like a code editing field.
kasper's source
What?