acl/src/main/java/org/springframework/security/acls/jdbc/AclClassIdUtils.java
private Long convertToLong(Serializable identifier) {
		Long idAsLong;
		if (canConvertFromStringTo(Long.class)) {
			idAsLong = conversionService.convert(identifier, Long.class);
		} else {
			idAsLong = Long.valueOf(identifier.toString());
		}
		return idAsLong;
	}
private Long convertToLong(Serializable identifier) {
		Long idAsLong;
		if (canConvertFromStringTo(Long.class)) {
			idAsLong = conversionService.convert(identifier, Long.class);
		} else {
			idAsLong = Long.valueOf(identifier.toString());
		}
		return idAsLong;
	}
Converts to a {@link Long}, attempting to use the {@link ConversionService} if available.
@param identifier    The identifier
@return Long version of the identifier
@throws NumberFormatException if the string cannot be parsed to a long.
@throws org.springframework.core.convert.ConversionException if a conversion exception occurred
@throws IllegalArgumentException if targetType is null