lombok @ExtensionMethod sample.

gistfile1.java

import lombok.experimental.ExtensionMethod;

// @ExtensionMethod({ String.class }) // Compile Error.
@ExtensionMethod({ Extensions.class })
public class Main {
    public static void main(String[] args) {
        System.out.println("Hello, %s".format("World.")); // => "Hello, World."
    }
}

class Extensions {
    public static String format(String format, Object ... args) {
        return String.format(format, args);
    }
}