Updated Code

@mezz.jei.api.JeiPlugin
public class JeiPlugin implements IModPlugin {
    public static IJeiHelpers jeiHelper;
    @Override
    public ResourceLocation getPluginUid() {
        return new ResourceLocation("jeitest", "default");
    }

    @Override
    public void registerCategories(IRecipeCategoryRegistration registration) {
        jeiHelper = registration.getJeiHelpers();
        registration.addRecipeCategories(new InfuseBlockJeiCategory(jeiHelper.getGuiHelper()));
    }

    @Override
    public void registerRecipes(IRecipeRegistration registration) {
        registration.addRecipes(generateInfuseBlockRecipes(), InfuseBlockJeiCategory.Uid);
        registration.addRecipes(generateInfuseBlockRecipes2(), InfuseBlockJeiCategory.Uid);
    }

    private List<InfuseBlockJeiCategory.InfuseBlockRecipeWrapper> generateInfuseBlockRecipes() {
        List<InfuseBlockJeiCategory.InfuseBlockRecipeWrapper> recipes = new ArrayList<>();
        ArrayList<ItemStack> inputs = new ArrayList<>();
        ArrayList<ItemStack> outputs = new ArrayList<>();
        inputs.add(new ItemStack(Items.DIRT));
        outputs.add(new ItemStack(Items.DIAMOND));
        recipes.add(new InfuseBlockJeiCategory.InfuseBlockRecipeWrapper(inputs, outputs));
        return recipes;
    }

        private List<InfuseBlockJeiCategory.InfuseBlockRecipeWrapper> generateInfuseBlockRecipes2() {
        List<InfuseBlockJeiCategory.InfuseBlockRecipeWrapper> recipes = new ArrayList<>();
        ArrayList<ItemStack> inputs = new ArrayList<>();
        ArrayList<ItemStack> outputs = new ArrayList<>();
        inputs.add(new ItemStack(Items.STONE));
        outputs.add(new ItemStack(Items.EMERALD));
        recipes.add(new InfuseBlockJeiCategory.InfuseBlockRecipeWrapper(inputs, outputs));
        return recipes;
    }

    @Override
    public void registerRecipeCatalysts(IRecipeCatalystRegistration registration) {
        registration.addRecipeCatalyst(new ItemStack(InfuseBenchBlock.block), InfuseBlockJeiCategory.Uid);
    }
    public static class InfuseBlockJeiCategory implements IRecipeCategory<InfuseBlockJeiCategory.InfuseBlockRecipeWrapper> {
        private static ResourceLocation Uid = new ResourceLocation("jeitest", "infuseblockcategory");
        private static final int input1 = 0; // THE NUMBER = SLOTID
        private static final int output1 = 1; // THE NUMBER = SLOTID
        // ...
        private final String title;
        private final IDrawable background;

        public InfuseBlockJeiCategory(IGuiHelper guiHelper) {
            this.title = "Infuse Bench";
            this.background = guiHelper.createDrawable(new ResourceLocation("jeitest", "textures/infuse_bench_gui.png"), 0, 0, 175, 166);
        }

        @Override
        public ResourceLocation getUid() {
            return Uid;
        }

        @Override
        public Class<? extends InfuseBlockRecipeWrapper> getRecipeClass() {
            return InfuseBlockJeiCategory.InfuseBlockRecipeWrapper.class;
        }

        @Override
        public String getTitle() {
            return title;
        }

        @Override
        public IDrawable getBackground() {
            return background;
        }

        @Override
        public IDrawable getIcon() {
            return null;
        }

        @Override
        public void setIngredients(InfuseBlockRecipeWrapper recipeWrapper, IIngredients iIngredients) {
            iIngredients.setInputs(VanillaTypes.ITEM, recipeWrapper.getInput());
            iIngredients.setOutputs(VanillaTypes.ITEM, recipeWrapper.getOutput());
            // ...
        }

        @Override
        public void draw(InfuseBlockRecipeWrapper recipe, double mouseX, double mouseY) {
            FontRenderer fontRenderer = Minecraft.getInstance().fontRenderer;
            ItemStack recipeOutput = (ItemStack) recipe.output.get(0);
            System.out.println(recipeOutput.getItem() == Items.DIAMOND);

        }
        @Override
        public void setRecipe(IRecipeLayout iRecipeLayout, InfuseBlockRecipeWrapper recipeWrapper, IIngredients iIngredients) {
            IGuiItemStackGroup stacks = iRecipeLayout.getItemStacks();
            stacks.init(input1, true, 37, 32);
            stacks.set(input1, iIngredients.getInputs(VanillaTypes.ITEM).get(0));
            // ,,,

            stacks.init(output1, false, 118, 28);
            stacks.set(output1, iIngredients.getOutputs(VanillaTypes.ITEM).get(0));
            // ...
        }
        public static class InfuseBlockRecipeWrapper {
            private ArrayList input;
            private ArrayList output;

            public InfuseBlockRecipeWrapper(ArrayList input, ArrayList output) {
                this.input = input;
                this.output = output;
            }


            public ArrayList getInput() {
                return input;
            }

            public ArrayList getOutput() {
                return output;
            }
        }
    }
}