SPIGOT-4164: Treat new _AIR blocks as air

src/main/java/org/bukkit/craftbukkit/block/CraftBlock.java

@@ -489,7 +489,7 @@ public class CraftBlock implements Block {
     }
 
     public boolean isEmpty() {
-        return getType() == Material.AIR;
+        return getNMS().isAir();
     }
 
     public boolean isLiquid() {

src/main/java/org/bukkit/craftbukkit/entity/CraftLivingEntity.java

@@ -1,5 +1,6 @@
 package org.bukkit.craftbukkit.entity;
 
+import com.google.common.collect.Sets;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Iterator;
@@ -134,6 +135,9 @@ public class CraftLivingEntity extends CraftEntity implements LivingEntity {
     }
 
     private List<Block> getLineOfSight(Set<Material> transparent, int maxDistance, int maxLength) {
+        if (transparent == null) {
+            transparent = Sets.newHashSet(Material.AIR, Material.CAVE_AIR, Material.VOID_AIR);
+        }
         if (maxDistance > 120) {
             maxDistance = 120;
         }
@@ -146,16 +150,10 @@ public class CraftLivingEntity extends CraftEntity implements LivingEntity {
                 blocks.remove(0);
             }
             Material material = block.getType();
-            if (transparent == null) {
-                if (!material.equals(Material.AIR)) {
-                    break;
-                }
-            } else {
             if (!transparent.contains(material)) {
                 break;
             }
         }
-        }
         return blocks;
     }