#3584: Handle conversion of mixed NBT lists to json

protocol/src/main/java/net/md_5/bungee/protocol/TagUtil.java

@@ -124,9 +124,11 @@ public final class TagUtil
                     for ( JsonElement jsonEl : jsonArray )
                     {
                         SpecificTag subTag = fromJson( jsonEl );
-                        if ( subTag.tagType() != listType )
+                        if ( !( subTag instanceof CompoundTag ) )
                         {
-                            throw new IllegalArgumentException( "Cannot convert mixed JsonArray to Tag" );
+                            CompoundTag wrapper = new CompoundTag();
+                            wrapper.add( "", subTag );
+                            subTag = wrapper;
                         }
 
                         tagItems.add( subTag );
@@ -179,6 +181,20 @@ public final class TagUtil
                 JsonArray jsonList = new JsonArray( items.size() );
                 for ( SpecificTag subTag : items )
                 {
+                    if ( subTag instanceof CompoundTag )
+                    {
+                        CompoundTag compound = (CompoundTag) subTag;
+                        if ( compound.size() == 1 )
+                        {
+                            SpecificTag first = (SpecificTag) compound.get( "" );
+                            if ( first != null )
+                            {
+                                jsonList.add( toJson( first ) );
+                                continue;
+                            }
+                        }
+                    }
+
                     jsonList.add( toJson( subTag ) );
                 }
 

protocol/src/test/java/net/md_5/bungee/protocol/TagUtilTest.java

@@ -0,0 +1,29 @@
+package net.md_5.bungee.protocol;
+
+import static org.junit.jupiter.api.Assertions.*;
+import com.google.gson.Gson;
+import com.google.gson.JsonElement;
+import org.junit.jupiter.api.Test;
+import se.llbit.nbt.SpecificTag;
+
+public class TagUtilTest
+{
+
+    private static final Gson GSON = new Gson();
+
+    private static void testDissembleReassemble(String json)
+    {
+        JsonElement parsedJson = GSON.fromJson( json, JsonElement.class );
+        SpecificTag nbt = TagUtil.fromJson( parsedJson );
+        JsonElement convertedElement = TagUtil.toJson( nbt );
+
+        String convertedJson = GSON.toJson( convertedElement );
+        assertEquals( json, convertedJson );
+    }
+
+    @Test
+    public void testStringLiteral()
+    {
+        testDissembleReassemble( "{\"text\":\"\",\"extra\":[\"hello\",{\"text\":\"there\",\"color\":\"#ff0000\"},{\"text\":\"friend\",\"font\":\"minecraft:default\"}]}" );
+    }
+}