Gets the list of Leadtools.Medical.ExternalStore.DataAccessLayer.DataTypes.ExternalStoreInstance that need to be cleared from the 'Local Store'
expirationDays
Number of days the instance remains in the 'Local Store' before it expires (i.e. deleted)
the list of Leadtools.Medical.ExternalStore.DataAccessLayer.DataTypes.ExternalStoreInstance that need to be cleared from the 'Local Store'