Support resizing of element metadata

Author: NebelNidas

Diff for: src/main/java/net/fabricmc/mappingio/tree/MemoryMappingTree.java

@@ -702,7 +702,7 @@ private Entry<?> getCurrentEntry(MappedElementKind targetKind) {
 			entry = currentEntry;
 		}
 
-		if (entry == null) throw new UnsupportedOperationException("Tried to visit comment before owning target");
+		if (entry == null) throw new UnsupportedOperationException("Tried to visit element content before owning target");
 		return entry;
 	}
 
@@ -745,6 +745,10 @@ public void setDstName(String name, int namespace) {
 
 		void resizeDstNames(int newSize) {
 			dstNames = Arrays.copyOf(dstNames, newSize);
+
+			for (Map.Entry<String, String[]> entry : metadata.entrySet()) {
+				entry.setValue(Arrays.copyOf(entry.getValue(), newSize));
+			}
 		}
 
 		void updateDstNames(int[] map) {