/** * Adds and returns cross-reference * * @param ProteinXref Cross-reference to add * @return Cross-reference * @throws IllegalArgumentException if ProteinXref is null */ public ProteinXref addCrossReference(ProteinXref ProteinXref) throws IllegalArgumentException { if (ProteinXref == null) { throw new IllegalArgumentException("'ProteinXref' must not be null"); } crossReferences.add(ProteinXref); ProteinXref.setProtein(this); return ProteinXref; }