code: public Integer getAsNullableInteger(String key) {
  		Object value = getAsObject(key);
  		return IntegerConverter.toNullableInteger(value);
  	}
docs: Converts map element into an integer or returns null if conversion is not
  possible.
  
  @param key a key of element to get.
  @return integer value of the element or null if conversion is not supported.
  
  @see IntegerConverter#toNullableInteger(Object)