How to add bossbar to the mobs

I am making a mod using Forge for Minecraft 1.15.2. I made a simple mob so far. Now I want to add a bossbar to it but I don't know how to do it. Also I couldn't find any helpful topic or video about bossbars. 

Any advice or help?

Here's my current code : 

package com.fantalatone.buggytheclown.entities;

import net.minecraft.entity.AgeableEntity;
import net.minecraft.entity.EntityType;
import net.minecraft.entity.MobEntity;
import net.minecraft.entity.SharedMonsterAttributes;
import net.minecraft.entity.ai.attributes.AttributeMap;
import net.minecraft.entity.ai.attributes.AttributeMap;
import net.minecraft.entity.ai.goal.*;
import net.minecraft.entity.effect.LightningBoltEntity;
import net.minecraft.entity.monster.IMob;
import net.minecraft.entity.monster.MonsterEntity;
import net.minecraft.entity.passive.AnimalEntity;
import net.minecraft.world.World;
import net.minecraftforge.api.distmarker.Dist;
import net.minecraftforge.api.distmarker.OnlyIn;


public class Buggy extends MonsterEntity implements IMob {

    private double health = 0.0d;

    public Buggy(EntityType<? extends MonsterEntity> type, World worldIn) {
        super(type, worldIn);
    }

    @Override
    protected void registerAttributes() {
        super.registerAttributes();
        this.getAttribute(SharedMonsterAttributes.MAX_HEALTH).setBaseValue(120D);
        this.getAttribute(SharedMonsterAttributes.MOVEMENT_SPEED).setBaseValue(0.5D);
        this.getAttribute(SharedMonsterAttributes.KNOCKBACK_RESISTANCE).setBaseValue(0.2D);
        this.getAttribute(SharedMonsterAttributes.ATTACK_DAMAGE).setBaseValue(8D);
    }

    @Override
    protected void registerGoals() {
        super.registerGoals();
        this.goalSelector.addGoal(0, new SwimGoal(this));
        this.goalSelector.addGoal(1, new PanicGoal(this, 1D));
        this.goalSelector.addGoal(2, new LookRandomlyGoal(this));
        this.goalSelector.addGoal(1, new WaterAvoidingRandomWalkingGoal(this, 1D));
    }

    @Override
    protected void updateAITasks() {
        super.updateAITasks();
    }

    @Override
    public void livingTick() {
        super.livingTick();
        if (!this.world.isRemote) {
            health = this.getHealth();
        }
    }

    @Override
    public void onStruckByLightning(LightningBoltEntity lightningBolt) {
        this.setGlowing(true);
    }
}