@Override
  public byte[] engineExport(int length, byte[] exporterContext) {
    checkInitialised();
    long maxLength = hpkeSuite.getKdf().maxExportLength();
    if (length < 0 || length > maxLength) {
      throw new IllegalArgumentException("Export length must be between 0 and "
              + maxLength + ", but was " + length);
    }
    return NativeCrypto.EVP_HPKE_CTX_export(ctx, exporterContext, length);
  }
Implementation of {@link HpkeSpi}.  Should not be used directly, but rather by one
of the subclasses of {@link HpkeContext}.
common/src/main/java/org/conscrypt/HpkeImpl.java