fix portal linking in upgraded chunks (fixes #7419) (#7438)

Author: jpenilla

patches/server/0744-Optimise-general-POI-access.patch

@@ -939,10 +939,10 @@ index ff6cadec530dedf9efc5d6226e48a096a1073ad6..d73b99d7fde724da4503b5176c3ad7b0
              return Optional.empty();
          } else {
 diff --git a/src/main/java/net/minecraft/world/level/portal/PortalForcer.java b/src/main/java/net/minecraft/world/level/portal/PortalForcer.java
-index ed79058696eb26a89b9d4116821840dbad9ea449..d990d1652b71205816d678618bf360a60f309ad2 100644
+index ed79058696eb26a89b9d4116821840dbad9ea449..8f147cd9798779eb2a72f444bf7fcb6c3cdc4971 100644
 --- a/src/main/java/net/minecraft/world/level/portal/PortalForcer.java
 +++ b/src/main/java/net/minecraft/world/level/portal/PortalForcer.java
-@@ -51,18 +51,40 @@ public class PortalForcer {
+@@ -51,18 +51,41 @@ public class PortalForcer {
          // int i = flag ? 16 : 128;
          // CraftBukkit end
 
@@ -968,7 +968,8 @@ index ed79058696eb26a89b9d4116821840dbad9ea449..d990d1652b71205816d678618bf360a6
 +            },
 +            (BlockPos pos) -> {
 +                net.minecraft.world.level.chunk.ChunkAccess lowest = this.level.getChunk(pos.getX() >> 4, pos.getZ() >> 4, net.minecraft.world.level.chunk.ChunkStatus.EMPTY);
-+                if (!lowest.getStatus().isOrAfter(net.minecraft.world.level.chunk.ChunkStatus.FULL)) {
++                if (!lowest.getStatus().isOrAfter(net.minecraft.world.level.chunk.ChunkStatus.FULL)
++                    && (lowest.getBelowZeroRetrogen() == null || !lowest.getBelowZeroRetrogen().targetStatus().isOrAfter(net.minecraft.world.level.chunk.ChunkStatus.HEIGHTMAPS))) {
 +                    // why would we generate the chunk?
 +                    return false;
 +                }