[SPIGOT-946] Begin making use of access transforms to simplify patching.

nms-patches/MobSpawnerAbstract.patch

@@ -1,6 +1,6 @@
 --- a/net/minecraft/server/MobSpawnerAbstract.java
 +++ b/net/minecraft/server/MobSpawnerAbstract.java
-@@ -4,9 +4,11 @@
+@@ -4,6 +4,8 @@
  import java.util.Iterator;
  import java.util.List;
  
@@ -8,17 +8,10 @@
 +
  public abstract class MobSpawnerAbstract {
  
--    private int spawnDelay = 20;
-+    public int spawnDelay = 20; // CraftBukkit - public
-     private String mobName = "Pig";
-     private final List<MobSpawnerAbstract.a> mobs = Lists.newArrayList();
-     private MobSpawnerAbstract.a spawnData;
-@@ -22,8 +24,13 @@
+     public int spawnDelay = 20;
+@@ -24,6 +26,11 @@
  
-     public MobSpawnerAbstract() {}
- 
--    private String getMobName() {
-+    public String getMobName() { // CraftBukkit - public
+     public String getMobName() {
          if (this.i() == null) {
 +            // CraftBukkit start - fix NPE
 +            if (this.mobName == null) {