How to integrate block and fluid features?

[AntonIXO]

I've tried to add this into server startup code:

VanillaReimplementation vri = VanillaReimplementation.hook(MinecraftServer.process());
vri.feature(FluidSimulationFeature.class);
VanillaBlocks.registerAll(vri);

But it results in:

Exception in thread "main" java.lang.NullPointerException: Feature class io.github.togar2.fluids.FluidSimulationFeature has not loaded yet.
        at java.base/java.util.Objects.requireNonNull(Objects.java:360)
        at net.minestom.vanilla.VanillaReimplementationImpl.feature(VanillaReimplementationImpl.java:87)
        at org.minebit.Main.main(Main.java:68)

How to integrate features? What better to use: vri.feature or .registerAll(vri) and why it does not loading needed class?