PaperMC/paper-server/nms-patches/net/minecraft/world/entity/EntityAgeable.patch

--- a/net/minecraft/world/entity/EntityAgeable.java
+++ b/net/minecraft/world/entity/EntityAgeable.java
@@ -19,6 +19,7 @@
     protected int age;
     protected int forcedAge;
     protected int forcedAgeTimer;
+    public boolean ageLocked; // CraftBukkit
 
     protected EntityAgeable(EntityTypes<? extends EntityAgeable> entitytypes, World world) {
         super(entitytypes, world);
@@ -102,6 +103,7 @@
         super.addAdditionalSaveData(nbttagcompound);
         nbttagcompound.putInt("Age", this.getAge());
         nbttagcompound.putInt("ForcedAge", this.forcedAge);
+        nbttagcompound.putBoolean("AgeLocked", this.ageLocked); // CraftBukkit
     }
 
     @Override
@@ -109,6 +111,7 @@
         super.readAdditionalSaveData(nbttagcompound);
         this.setAge(nbttagcompound.getInt("Age"));
         this.forcedAge = nbttagcompound.getInt("ForcedAge");
+        this.ageLocked = nbttagcompound.getBoolean("AgeLocked"); // CraftBukkit
     }
 
     @Override
@@ -123,7 +126,7 @@
     @Override
     public void aiStep() {
         super.aiStep();
-        if (this.level.isClientSide) {
+        if (this.level.isClientSide || ageLocked) { // CraftBukkit
             if (this.forcedAgeTimer > 0) {
                 if (this.forcedAgeTimer % 4 == 0) {
                     this.level.addParticle(Particles.HAPPY_VILLAGER, this.getRandomX(1.0D), this.getRandomY() + 0.5D, this.getRandomZ(1.0D), 0.0D, 0.0D, 0.0D);