This allows for an alternative, or non-default query to be created / used to find an offer code by
a code string. An implementor may wish to use a different named query, or add a filter.
Implementors MUST return one of: ExtensionResultStatusType.HANDLED, ExtensionResultStatusType.HANDLED_STOP, or
ExtensionResultStatusType.HANDLED or ExtensionResultStatusType.HANDLED_STOP is returned,
the resultHolder must be set with a valid instance of javax.persistence.Query. The cacheable and
cacheRegion properties are hints and may be ignored by the implementor.