REST client doesn't work with Grails 2.5.x and using accept("application/json") to parse REST JSON responses. The issue is in grails/grails-data-mapping/grails-datastore-rest-client but grails-rest-client-builder will need to use a newer version of org.grails:grails-datastore-rest-client once the fix is merged upstream. I think it's likely an issue in Grails 3.x as well, but I have not confirmed this by trying the plugin with Grails 3.
REST client doesn't work with Grails 2.5.x and using accept("application/json") to parse REST JSON responses. The issue is in grails/grails-data-mapping/grails-datastore-rest-client but grails-rest-client-builder will need to use a newer version of org.grails:grails-datastore-rest-client once the fix is merged upstream. I think it's likely an issue in Grails 3.x as well, but I have not confirmed this by trying the plugin with Grails 3.
The fixes are contained here in a pull request for grails-datastore-rest-client: https://github.com/grails/grails-data-mapping/pull/591
and here, which just shows my grails-datastore-rest-client fork using the above forked/patched grails-datastore-rest-client: https://github.com/grails-plugins/grails-rest-client-builder/compare/master...ucidentity:v2.1.1-grails2.5-fix?expand=1
Note that https://maven.calnet.berkeley.edu/artifactory/all/ is not a public repository, so in order to get it working locally, you'll need to build https://github.com/ucidentity/grails-data-mapping/tree/3.x-grails2.5-fix-ucb and deploy to your local maven repository.