This guide set your programming environment for developing JuicyRaspberryPie plugin for Spigot. Please note as an example I use version 1.16.5, which at the time of this writing is the latest version of Spigot. You should replace 1.16.5 with whatever version you want to use. Also here I use JDK version 11, but you can use any Java version from 8 onward.
In a command window (cmd.exe or powershell, or a Linux terminal):
mkdir mc1.16.5
cd mc1.16.5
mkdir build
mkdir run
cd build
Download BuildTools.jar into build directory, then:
java -jar BuildTools.jar --rev 1.16.5
Copy spigot-1.16.5.jar to run directory and rename it to just spigot.jar
Create file start-server-win.bat with content:
echo off
java -Xms8G -Xmx8G -jar spigot.jar
pause
Run start-server-win.bat. If it displays error message like main ERROR Unable to locate appender "SysOut" for logger config "root", do chcp 437, then start-server-win.bat.
Change eula.txt run start-server-win.bat again, type stop to exit.
Open File -> Settings, select Plugins, install "Minecraft Development" plugin.
Clone or download this repo, then in IntelliJ Idea, open File -> Open..., open JuicyRaspberryPie/bukkit. The project is now opened.
Edit pom.xml, change "Version" and "SpigotVersion" to 1.16.5 or whatever you're using.
Open File -> "Project Structure", in "Project Settings" -> Artifacts, add 'Jar (from modules with dependencies...), click "OK". In "Output Directory", specify output jar location, for example: E:\mcdev\mc1.16.5\run\plugins, check include in project build.
Click Run -> "Edit Configurations...", add a "Jar Application" called "spigot", then in "Path to Jar", enter or find spigot.jar location, for example:
E:\mcdev\mc1.16.5\run\spigot.jar.
Click build icon (hammer) or Build -> "Build Project".