public Builder throwableFormatter(ThrowableFormatter throwableFormatter) {
            this.throwableFormatter = throwableFormatter;
            return this;
        }
Set the throwable formatter when {@link Logger} log a message with throwable.

@param throwableFormatter the throwable formatter when {@link Logger} log a message with
                          throwable
@return the builder
android/android_framework/base/src/main/java/com/elvishew/xlog/Logger.java