ModTagProvider

public class ModTagProvider implements ICapabilitySerializable<FloatNBT>, IModTag {
    private float mod_tag;

    public ModTagProvider() {
        this.mod_tag = 0;
    }

    @Override
    public void set(float floatIn) { this.mod_tag = floatIn; }

    @Override
    public float get() {
        return this.mod_tag;
    }

    @CapabilityInject(IModTag.class)
    public static final Capability<IModTag> MOD_TAG = null;

    private LazyOptional<IModTag> instance = LazyOptional.of(MOD_TAG::getDefaultInstance);

    @Override
    public <T> LazyOptional<T> getCapability(Capability<T> cap, Direction side) {
        return cap == MOD_TAG ? instance.cast() : LazyOptional.empty();
    }

    @Override
    public FloatNBT serializeNBT() {
        return (FloatNBT) MOD_TAG.getStorage().writeNBT(
                MOD_TAG, instance.orElseThrow(
                        () -> new IllegalArgumentException("LazyOptional cannot be empty!")),
                null);
    }

    @Override
    public void deserializeNBT(FloatNBT nbt) {
        MOD_TAG.getStorage().readNBT(
                MOD_TAG, instance.orElseThrow(
                        () -> new IllegalArgumentException("LazyOptional cannot be empty!")),
                null, nbt);
    }
}