message: Change keyboardIcon type from string to ReactNode.
diff: -import { ComponentClass } from 'react';
  +import { ComponentClass, ReactNode } from 'react';
  import { DateType } from '../constants/prop-types'
  import { TextFieldProps } from 'material-ui/TextField';
  import { Omit } from 'material-ui'
  @@ -20,7 +20,7 @@ export interface DateTextFieldProps extends Omit<TextFieldProps, 'onChange' | 'v
  invalidLabel?: string;
  emptyLabel?: string;
  labelFunc?: (date: Moment, invalidLabel: string) => string;
  - keyboardIcon?: string;
  + keyboardIcon?: ReactNode;
  invalidDateMessage?: string;
  clearable?: boolean;
  }
  