Class deserializer and serialiazer to YAML

ClassYamlConfiguration.java

import org.bukkit.configuration.file.FileConfiguration;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.util.List;
import java.util.function.BiConsumer;
import java.util.function.Function;
import java.util.stream.Collectors;

/**
 * Deserialize a public static fields of a classe
 *
 * Deserialize public static fields de uma classe
 * 
 * @author DevSrSouza
 * @version 1.0
 *
 * https://github.com/DevSrSouza/
 * You can find updates here https://gist.github.com/DevSrSouza
 */
public class ClassYamlConfiguration {

    /**
     * If you want to translate & to § on load and § to & on save let this true
     *
     * Se voce querer converter as cores em String deixe true
     */
    public static boolean AUTO_CONVERT_COLORS = true;


    /**
     * If on config have the field name he loads to the field the value
     * else he set to the config the default value of field
     * 
     * @param clazz your class model
     * @param fileConfiguration your config
     * @return true if set something on the config(save the configuration if is true)
     */
    public static boolean loadAndSetDefault(Class clazz, FileConfiguration fileConfiguration) {
        return loadAndSetDefault(clazz,
                (path) -> fileConfiguration.get(path),
                (path, value) -> fileConfiguration.set(path, value));
    }
    
    public static boolean loadAndSetDefault(Class clazz, Function<String, Object> get, BiConsumer<String, Object> set) {
        boolean anyModification = false;
        for(Field f : clazz.getFields()) {

            if(Modifier.isStatic(f.getModifiers())) {
                Object template = null;
                try{
                    template = f.get(null);
                }catch (Exception ex) {
                    continue;
                }
                if(f.getType().equals(Class.class)) {
                    boolean modificou = loadAndSetDefault((Class)template, (path) ->
                                    get.apply(f.getName() + "." + path),
                            (path, value) -> set.accept(f.getName() + "." + path, value));
                    if(modificou) anyModification=true;
                }else{
                    Object got = get.apply(f.getName());
                    if(template != null && got == null) {
                        anyModification = true;
                        if (f.getType().equals(String.class)) {
                            Object fixColor = AUTO_CONVERT_COLORS ? ((String) template).replace('§', '&') : template;
                            set.accept(f.getName(), fixColor);
                            got = fixColor;
                        } else if (f.getType().equals(List.class)
                                && ((Class<?>) ((ParameterizedType) f.getGenericType()).getActualTypeArguments()[0]).equals(String.class)) {
                            Object fixColor = AUTO_CONVERT_COLORS ?
                                    ((List<String>) template).stream()
                                            .map(s->s.replace('§', '&')).collect(Collectors.toList())
                                    : template;
                            set.accept(f.getName(), fixColor);
                            got = fixColor;
                        } else {
                            set.accept(f.getName(), template);
                        }

                    }
                    if(got != null) {
                        try {
                            if(f.getType().equals(String.class)) {
                                f.set(null, AUTO_CONVERT_COLORS ? ((String)got).replace('&', '§') : got);
                            }else if (f.getType().equals(List.class)
                                    && ((Class<?>) ((ParameterizedType) f.getGenericType()).getActualTypeArguments()[0]).equals(String.class)) {
                                f.set(null, AUTO_CONVERT_COLORS ?
                                        ((List<String>) got).stream()
                                                .map(s->s.replace('&', '§')).collect(Collectors.toList())
                                        : got);
                            }else {
                                f.set(null, got);
                            }
                        } catch (Exception e) {
                            continue;
                        }
                    }
                }
            }
        }
        return anyModification;
    }
}

config.yml

# Target default
# Isso foi como ficou com os padroes
server_name: SamplePlugin
default_int_value: 50
messages:
  on_server_start: '&cServidor iniciando...'

Sample.java

import org.bukkit.configuration.file.FileConfiguration;
import org.bukkit.configuration.file.YamlConfiguration;
import org.bukkit.plugin.java.JavaPlugin;

import java.io.File;
import java.io.IOException;

public class Sample extends JavaPlugin {

    @Override
    public void onEnable() {
        
        getDataFolder().mkdirs();
        File file = new File(getDataFolder(), "config.yml");
        FileConfiguration config = null;
        
        
        if (!file.exists()) {
            try {
                file.createNewFile();
            } catch (IOException e) { e.printStackTrace(); }
        }

        config = YamlConfiguration.loadConfiguration(file);

        if(ClassYamlConfiguration.loadAndSetDefault(MyConfig.class, config)) {
            try {
                config.save(file);
            } catch (IOException e) { e.printStackTrace(); }
        }
    }

    public static class MyConfig {
        public static String server_name = "SamplePlugin";
        public static int default_int_value = 50;
        
        public static Class messages = MessagesConfig.class; 
    }

    public static class MessagesConfig {
        public static String on_server_start = "§cServidor iniciando...";
    }
}