Gradlew HelloWorld

Hello, ive been trying to use javafx on raspberry pi. I have javafx running on raspbian and working with the HelloWorld sample included in jfxports (i see the screen and button). I then opened the in a IDE and copied and pasted my code in (which involves using GPIO and PI4J). when i run gradlew :HelloWorld:build, instead of building the jar file in the build folder i receive this error. Can someone please tell me how to solve the gpio error. It doesnt recognize the gpio commands, somehow i need to add the pi4j jar files to the gradlew so it doesn’t throw an error.