if (towgs84 != null)
return parseToWGS84(towgs84, ellps);
String datumId = parameters.get(Param.datum.key);
if (datumId != null) {
Datum datum = Projections.getDatum(datumId);
if (datum == null) throw new ProjectionConfigurationException(tr("Unknown datum identifier: ''{0}''", datumId));
return datum;
}
if (parameters.containsKey(Param.no_defs.key))
throw new ProjectionConfigurationException(tr("Datum required (+datum=*, +towgs84=* or +nadgrids=*)"));