private String getWARCMetadataRecord(MetaData m) {
   return unwrapFirst(warcMetadataRecord.extract(m), "-");
 }
 private String getWARCURL(MetaData m) {
   return unwrapFirst(warcURL.extract(m), "-");
 }
 private String getWARCType(MetaData m) {
   return unwrapFirst(warcType.extract(m), "-");
 }
 private String getEnvelopeFormat(MetaData m) {
   return unwrapFirst(formatSpec.extract(m), "-");
 }