Library in code folder doesn't work properly

I made this little library: GitHub

I have put the Maven build of this library into my code folder, and tried this:

import iliquid.exjs.*;

exJS js;

void setup() {
  js = new exJS();
  noLoop();
}

void draw() {
  js.loadScript(sketchPath() + "/data/script.js");
  js.addImport("java.lang.System", "system");
  js.initEngine();
  js.evalScript();
}

But I am getting errors like:

The function "loadScript(String)" doesn't exist

even though the function clearly exists in my library's code:

public void loadScript(String path) {
    try {
        script = new BufferedReader(new FileReader(path));
    } catch (FileNotFoundException e) {
        System.err.printf("(exJS) Error: Could not load script from file %s%n", path);
        e.printStackTrace();
    }
}

You might suggest that I should use the Eclipse Library Template. I don't want to, because I use IntelliJ (although it has an Eclipse project import feature, but this didn't happen with a previous library of mine, which was developed without the template like this one.)

What could be the cause of my problem?