code: public static synchronized X509CRLImpl intern(X509CRL c)
              throws CRLException {
          if (c == null) {
              return null;
          }
          boolean isImpl = c instanceof X509CRLImpl;
          byte[] encoding;
          if (isImpl) {
              encoding = ((X509CRLImpl)c).getEncodedInternal();
          } else {
              encoding = c.getEncoded();
          }
          X509CRLImpl newC = (X509CRLImpl)getFromCache(crlCache, encoding);
          if (newC != null) {
              return newC;
          }
          if (isImpl) {
              newC = (X509CRLImpl)c;
          } else {
              newC = new X509CRLImpl(encoding);
              encoding = newC.getEncodedInternal();
          }
          addToCache(crlCache, encoding, newC);
          return newC;
      }
docs: Return an interned X509CRLImpl for the given certificate.
  For more information, see intern(X509Certificate).