Fix ignoring maxUpStep method overrides on entities (#9583)

src/main/java/net/minecraftforge/common/extensions/IForgeEntity.java

@@ -203,13 +203,13 @@ public interface IForgeEntity extends ICapabilitySerializable<CompoundTag>
 
     /**
      * @return Return the height in blocks the Entity can step up without needing to jump
-     * This is the sum of vanilla's {@link Entity#maxUpStep} field and the current value
+     * This is the sum of vanilla's {@link Entity#maxUpStep()} method and the current value
      * of the {@link net.minecraftforge.common.ForgeMod#STEP_HEIGHT_ADDITION} attribute
      * (if this Entity is a {@link LivingEntity} and has the attribute), clamped at 0.
      */
     default float getStepHeight()
     {
-        float vanillaStep = self().maxUpStep;
+        float vanillaStep = self().maxUpStep();
         if (self() instanceof LivingEntity living)
         {
             AttributeInstance stepHeightAttribute = living.getAttribute(ForgeMod.STEP_HEIGHT_ADDITION.get());