From 9a8902d1fe26d492346c9e9a50ab99dd28e5d5fd Mon Sep 17 00:00:00 2001
From: "Dylan K. Taylor" <dktapps@pmmp.io>
Date: Tue, 19 Jul 2022 16:08:05 +0100
Subject: [PATCH] LegacyToStringMap: don't throw if the existing mapping is the
 same as the one we want to register this was making it inconvenient for
 plugins to use BlockIdMetaUpgrader->addMapping(), because the block legacy ID
 map contains IDs up to 1.16, but the table of mapped 1.12 blockstates only
 goes up to ... well ... 1.12. This left a gap of several versions' blocks
 unable to be mapped.

---
 src/data/bedrock/LegacyToStringIdMap.php | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/data/bedrock/LegacyToStringIdMap.php b/src/data/bedrock/LegacyToStringIdMap.php
index d808b35df..e5181e193 100644
--- a/src/data/bedrock/LegacyToStringIdMap.php
+++ b/src/data/bedrock/LegacyToStringIdMap.php
@@ -66,6 +66,9 @@ abstract class LegacyToStringIdMap{
 
 	public function add(string $string, int $legacy) : void{
 		if(isset($this->legacyToString[$legacy])){
+			if($this->legacyToString[$legacy] === $string){
+				return;
+			}
 			throw new \InvalidArgumentException("Legacy ID $legacy is already mapped to string " . $this->legacyToString[$legacy]);
 		}
 		$this->legacyToString[$legacy] = $string;