question: private void linkSignatures ( List < PdfSignatureOrDocTimestampInfo > signatures ) { List < PdfSignatureOrDocTimestampInfo > previousList = new ArrayList < PdfSignatureOrDocTimestampInfo > ( ) ; for ( PdfSignatureOrDocTimestampInfo sig : signatures ) { if ( CollectionUtils . isNotEmpty ( previousList ) ) { for ( PdfSignatureOrDocTimestampInfo previous : previousList ) { previous . addOuterSignature ( sig ) ; } } previousList . add ( sig ) ; } }
target:  This method links previous signatures to the new one. This is useful to get revision number and to know if a TSP is over the DSS dictionary