From jdk 7 onwards, new functionality was introduced which allows currency data to be overridden by the jre/lib/currency.data properties file (text file)

http://docs.oracle.com/javase/7/docs/api/java/util/Currency.html

This file doesn't allow for cutover dates to be specified. A simple timestamp (of UTC/GMT format) should be parsed on same line as currency data and, if present, the currency data is used over shipping JRE data if the current UTC time is post the specified timestamp.

Any exceptions in parsing the timestamp should mean that the entry is ignored and an error message is output to logger.