Updated Upstream (Bukkit/CraftBukkit)

Upstream has released updates that appears to apply and compile correctly.
This update has not been tested by PaperMC and as with ANY update, please do your own testing

Bukkit Changes:
39ce5d3a SPIGOT-4399: ItemMeta.equals broken with AttributeModifiers

CraftBukkit Changes:
1cf8b5dc SPIGOT-4400: Populators running on existing chunks
116cb9a1 SPIGOT-4399: Add attribute modifier equality test
5ee1c18a SPIGOT-4398: Set ASM7_EXPERIMENTAL flag

Spigot-Server-Patches/Don-t-call-getItemMeta-on-hasItemMeta.patch

@@ -24,7 +24,7 @@ index d6e6b9bed4..3966769c5f 100644
  
      static boolean hasItemMeta(net.minecraft.server.ItemStack item) {
 diff --git a/src/test/java/org/bukkit/craftbukkit/inventory/ItemMetaTest.java b/src/test/java/org/bukkit/craftbukkit/inventory/ItemMetaTest.java
-index ef9d40b8a0..a161993876 100644
+index e3065bf8d6..1b7790bf7e 100644
 --- a/src/test/java/org/bukkit/craftbukkit/inventory/ItemMetaTest.java
 +++ b/src/test/java/org/bukkit/craftbukkit/inventory/ItemMetaTest.java
 @@ -0,0 +0,0 @@ import static org.hamcrest.Matchers.*;
@@ -33,8 +33,8 @@ index ef9d40b8a0..a161993876 100644
  import java.util.Arrays;
 +import java.util.Collections; // Paper
  import java.util.List;
- import com.destroystokyo.paper.inventory.meta.ArmorStandMeta; // Paper
- import net.minecraft.server.Block;
+ import java.util.UUID;
+ 
 @@ -0,0 +0,0 @@ public class ItemMetaTest extends AbstractTestingBase {
          ItemStack pureBukkit = new ItemStack(Material.SHEARS);
          assertThat("Bukkit and craft stacks should be similar", craft.isSimilar(pureBukkit), is(true));