如何设置MUI DatePicker的占位符文本？

import React from 'react';
import { DatePicker, InputLabel, MenuItem } from '@material-ui/core';
import { MuiPickersUtilsProvider } from '@material-ui/pickers';
import DateFnsUtils from '@date-io/date-fns';

render() {
  return (
    <MuiPickersUtilsProvider utils={DateFnsUtils}>
      <InputLabel shrink htmlFor="mui-date-picker">
        选择日期
      </InputLabel>
      <DatePicker id="mui-date-picker" />
    </MuiPickersUtilsProvider>
  );
}

const styles = {
  inputLabel: {
    color: 'gray',
    fontSize: '14px',
  },
};

render() {
  return (
    <MuiPickersUtilsProvider utils={DateFnsUtils}>
      <InputLabel shrink htmlFor="mui-date-picker" style={styles.inputLabel}>
        选择日期
      </InputLabel>
      <DatePicker id="mui-date-picker" />
    </MuiPickersUtilsProvider>
  );
}