Subscribing to Client Events in Forge for Minecraft 1.15

ClientEventExample.java

// The value here should match an entry in the META-INF/mods.toml file
@Mod(YourMod.MODID)
public class YourMod
{
	public static final String MODID = "yourmod";
	
	public YourMod()
	{
		IEventBus modBus = FMLJavaModLoadingContext.get().getModEventBus();
		IEventBus forgeBus = MinecraftForge.EVENT_BUS;
		
		// use a layer of indirection when subscribing client events to avoid classloading client classes on server
    		DistExecutor.runWhenOn(Dist.CLIENT, () -> () -> ClientEventHandler.subscribeClientEvents(modBus, forgeBus));
	}
}

// this should be in a separate class somewhere! not the same class
public class ClientEventHandler
{
  	// use addListener to subscribe whatever client events you need
  	// check out net.minecraftforge.client.event for most of the client-only events
  
	public static void subscribeClientEvents(IEventBus modBus, IEventBus forgeBus)
	{
    		modBus.addListener(ClientEventHandler::onRegisterParticleFactories);
		modBus.addListener(ClientEventHandler::onClientSetup);
	}
  
	private static void onRegisterParticleFactories(ParticleFactoryRegisterEvent event)
	{
		Minecraft.getInstance().particles.registerFactory(MyParticleTypeDeferredRegistry.DUNGEON_PORTAL.get(), DungeonPortalParticle.Factory::new);
	}
	
	private static void onClientSetup(FMLClientSetupEvent event)
	{
    		// register entity and tile entity renderers here, set render layers of blocks
		RenderingRegistry.registerEntityRenderingHandler(MyEntitityDeferredRegistry.UNRELENTING_CUBE.get(), UnrelentingCubeEntityRenderer::new);
	}
}