code: public String getFbtraceId() {
      if (getRawErrorJson() != null && getRawErrorJson().get("error").isObject()) {
        JsonObject errorJson = getRawErrorJson().get("error").asObject();
        return errorJson.getString("fbtrace_id", "");
      }
  
      return "";
    }
docs: Gets the Facebook API error {@code fbtrace_id}.
  
  Internal support identifier. When reporting a bug related to a Graph API call, include the fbtrace_id to help us
  find log data for debugging.
  
  @return the Facebook API error {@code fbtrace_id}