I uploaded a .java model into the Mcreator workshop, but the workshop says that their is something wrong with the model.

I uploaded a .java model for a mob that I was creating from Blockbench, but when I went to run the game, it came up with an error message:

C:\Users\J5\MCreatorWorkspaces\blockycraftmod\src\main\java\net\mcreator\blockycraftmod\entity\PixieEntity.java:269: error: cannot find symbol       public void render(MatrixStack matrixStack, IVertexBuilder buffer, int packedLight, int packedOverlay, float red, float green, float blue,
                         ^
  symbol:   class MatrixStack
  location: class Modelcustom_model
C:\Users\J5\MCreatorWorkspaces\blockycraftmod\src\main\java\net\mcreator\blockycraftmod\entity\PixieEntity.java:269: error: cannot find symbol       public void render(MatrixStack matrixStack, IVertexBuilder buffer, int packedLight, int packedOverlay, float red, float green, float blue,
                                                  ^
  symbol:   class IVertexBuilder
  location: class Modelcustom_model
2 errors
FAILURE: Build failed with an exception.

Whenever I try to upload a .java model, it does this. I really need help on this.

Thanks.