I am trying to updating my code in 1.16 to 1.17, but I have some problems.

public class SmallMcbbsWikiMonsterModel extends EntityModel<SmallMcbbsWikiMonsterEntity> {
    private final ModelPart body;

    public SmallMcbbsWikiMonsterModel() {
        textureWidth = 64;
        textureHeight = 64;

        body = new ModelRenderer(this, 0, 0);
        body.addBox(-16.0F, -8.0F, 0.0F, 16.0F, 8.0F, 16.0F);
    }

    @Override
    @ParametersAreNonnullByDefault
    public void setupAnim(SmallMcbbsWikiMonsterEntity entityIn, float limbSwing, float limbSwingAmount, float ageInTicks, float netHeadYaw, float headPitch) {

    }

    @Override
    @ParametersAreNonnullByDefault
    public void renderToBuffer(PoseStack matrixStackIn, VertexConsumer bufferIn, int packedLightIn, int packedOverlayIn, float red, float green, float blue, float alpha) {
        body.render(matrixStackIn, bufferIn, packedLightIn, packedOverlayIn);
    }
}

These four things: textureWidth, textureHeight, ModelRenderer and ModelPart.addBox does not exist in 1.17. What are their names now?

The model is just a single cuboid, with nothing else.

Please help me to update my code. Thanks.

look at the SlimeModel for an example