https://docs.advntr.dev/minimessage/index.html + Java 21 String Templates

MiniMessageTemplate.java

import net.kyori.adventure.text.Component;
import net.kyori.adventure.text.minimessage.MiniMessage;

public final class MiniMessageTemplate {
    private MiniMessageTemplate() {}

    public static final StringTemplate.Processor<Component, RuntimeException> MM = stringTemplate -> {
        String interpolated = STR.process(stringTemplate);
        MiniMessage mm = MiniMessage.miniMessage();
        return mm.deserialize(interpolated);
    };
}

Usage.java

eventsHandler.addListener(PlayerBlockBreakEvent.class, event -> {
    Player player = event.getPlayer();
    LOG.info(STR."\{player.getUsername()} broke a block!");
    player.getInstance().sendMessage(MM."<rainbow>\{player.getUsername()} broke a block!</rainbow>");
});