void appendLog(String flattenedLog) {
            try {
                bufferedWriter.write(flattenedLog);
                bufferedWriter.newLine();
                bufferedWriter.flush();
            } catch (IOException e) {
                // Redirect to xposed.
                XposedBridge.log(flattenedLog);
            }
        }
Append the flattened log to the end of current opened log file.

@param flattenedLog the flattened log
android/android_framework/base/src/main/java/com/elvishew/xlog/printer/file/FilePrinter.java