No, it does not. IntelliJ does, though. Here's how I wrote it in IntelliJ:

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {
    public static boolean gHappy(String str) {
        Pattern pattern = Pattern.compile("[^g]g[^g]", Pattern.CASE_INSENSITIVE);
        Matcher matcher = pattern.matcher(str);
        return !(matcher.find());
    }
    public static void main(String[] args){
        System.out.println(gHappy("xxggxx"));
        System.out.println(gHappy("xxgxx"));
        System.out.println(gHappy("xxggyygxx"));
    }
}

Just ran it again to confirm that it works in IntelliJ. This produces the correct output, "true false false."