code: public function getInputSpecification()
  	{
  		$datetimeElement = $this;
  
  		return array(
  			'name' => $this->getName(),
  			'required' => true,
  			'filters' => array(
  				array('name' => 'Zend\Filter\StringTrim'),
  				array(
  					'name' => 'Callback',
  					'options' => array(
  						'callback' => function ($value) use ($datetimeElement) {
  							if (!empty($value) && is_string($value)) {
  								return DateTime::createFromFormat($datetimeElement->getFormat(), $value);
  							}
  							return $value;
  						}
  					)
  				)
  			),
  			'validators' => $this->getValidators(),
  		);
  	}
docs: Provide default input rules for this element
  
  Attaches default validators for the datetime input.
  
  @return array