How to use

provideVersions

method

in

org.threeten.bp.zone.ZoneRulesProvider

/**
 * Gets the history of rules for the zone ID.
 * <p>
 * Time-zones are defined by governments and change frequently.
 * This method allows applications to find the history of changes to the
 * rules for a single zone ID. The map is keyed by a string, which is the
 * version string associated with the rules.
 * <p>
 * The exact meaning and format of the version is provider specific.
 * The version must follow lexicographical order, thus the returned map will
 * be order from the oldest known rules to the newest available rules.
 * The default 'TZDB' group uses version numbering consisting of the year
 * followed by a letter, such as '2009e' or '2012f'.
 * <p>
 * Implementations must provide a result for each valid zone ID, however
 * they do not have to provide a history of rules.
 * Thus the map will always contain one element, and will only contain more
 * than one element if historical rule information is available.
 *
 * @param zoneId  the zone region ID as used by {@code ZoneId}, not null
 * @return a modifiable copy of the history of the rules for the ID, sorted
 *  from oldest to newest, not null
 * @throws ZoneRulesException if history cannot be obtained for the zone ID
 */
public static NavigableMap<String, ZoneRules> getVersions(String zoneId) {
  Jdk8Methods.requireNonNull(zoneId, "zoneId");
  return getProvider(zoneId).provideVersions(zoneId);
}

/**
 * Gets the history of rules for the zone ID.
 * <p>
 * Time-zones are defined by governments and change frequently.
 * This method allows applications to find the history of changes to the
 * rules for a single zone ID. The map is keyed by a string, which is the
 * version string associated with the rules.
 * <p>
 * The exact meaning and format of the version is provider specific.
 * The version must follow lexicographical order, thus the returned map will
 * be order from the oldest known rules to the newest available rules.
 * The default 'TZDB' group uses version numbering consisting of the year
 * followed by a letter, such as '2009e' or '2012f'.
 * <p>
 * Implementations must provide a result for each valid zone ID, however
 * they do not have to provide a history of rules.
 * Thus the map will always contain one element, and will only contain more
 * than one element if historical rule information is available.
 *
 * @param zoneId  the zone region ID as used by {@code ZoneId}, not null
 * @return a modifiable copy of the history of the rules for the ID, sorted
 *  from oldest to newest, not null
 * @throws ZoneRulesException if history cannot be obtained for the zone ID
 */
public static NavigableMap<String, ZoneRules> getVersions(String zoneId) {
  Jdk8Methods.requireNonNull(zoneId, "zoneId");
  return getProvider(zoneId).provideVersions(zoneId);
}