New event to allow mutating a baby entity based on it's parents (#3227)

src/test/java/net/minecraftforge/debug/BreedingTest.java

@@ -0,0 +1,24 @@
+package net.minecraftforge.debug;
+
+import net.minecraft.entity.passive.EntityCow;
+import net.minecraftforge.common.MinecraftForge;
+import net.minecraftforge.event.entity.living.BabyEntitySpawnEvent;
+import net.minecraftforge.fml.common.Mod;
+import net.minecraftforge.fml.common.event.FMLPreInitializationEvent;
+import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
+
+@Mod(modid = BreedingTest.MODID, name = "BreedingTest", version = "1.0")
+public class BreedingTest
+{
+  public static final String MODID = "breedingtest";
+
+  @Mod.EventHandler
+  public void preInit(FMLPreInitializationEvent event) {
+    MinecraftForge.EVENT_BUS.register(this);
+  }
+
+  @SubscribeEvent
+  public void onBabyBorn(BabyEntitySpawnEvent event) {
+    event.setChild(new EntityCow(event.getChild().worldObj));
+  }
+}