void completeTag() {
      if (this.tagState.isTag) {
        this.consumer.append(TokenParser.TAG_END);
        this.tagState = TagState.TEXT;
      }
    }
mark tag boundaries within the stack, without needing to mess with typing too much.
text-minimessage/src/main/java/net/kyori/adventure/text/minimessage/MiniMessageSerializer.java