SPIGOT-4526: Add conversion time API for Zombie & subclasses

By: md_5 <git@md-5.net>

paper-api/src/main/java/org/bukkit/entity/PigZombie.java

@@ -33,4 +33,28 @@ public interface PigZombie extends Zombie {
      * @return True if the zombie is angry, otherwise false.
      */
     boolean isAngry();
+
+    /**
+     * <b>Not applicable to this entity</b>
+     *
+     * @return false
+     */
+    @Override
+    public boolean isConverting();
+
+    /**
+     * <b>Not applicable to this entity</b>
+     *
+     * @return UnsuppotedOperationException
+     */
+    @Override
+    public int getConversionTime();
+
+    /**
+     * <b>Not applicable to this entity</b>
+     *
+     * @param time unused
+     */
+    @Override
+    public void setConversionTime(int time);
 }