code: private void indexCRL(X509CRL crl) {
          X500Principal issuer = crl.getIssuerX500Principal();
          Object oldEntry = crlIssuers.put(issuer, crl);
          if (oldEntry != null) { // assume this is unlikely
              if (oldEntry instanceof X509CRL) {
                  if (crl.equals(oldEntry)) {
                      return;
                  }
                  List<X509CRL> list = new ArrayList<>(2);
                  list.add(crl);
                  list.add((X509CRL)oldEntry);
                  crlIssuers.put(issuer, list);
              } else {
                  // See crlIssuers javadoc.
                  @SuppressWarnings("unchecked")
                  List<X509CRL> list = (List<X509CRL>)oldEntry;
                  if (list.contains(crl) == false) {
                      list.add(crl);
                  }
                  crlIssuers.put(issuer, list);
              }
          }
      }
docs: Add an X509CRL to the index.