@AccessesPartialKey
  static com.google.crypto.tink.aead.AesGcmSivKey createAesGcmSivKeyFromRandomness(
      AesGcmSivParameters parameters,
      InputStream stream,
      @Nullable Integer idRequirement,
      SecretKeyAccess access)
      throws GeneralSecurityException {
    return com.google.crypto.tink.aead.AesGcmSivKey.builder()
        .setParameters(parameters)
        .setIdRequirement(idRequirement)
        .setKeyBytes(Util.readIntoSecretBytes(stream, parameters.getKeySizeBytes(), access))
        .build();
  }
This key manager generates new {@code AesGcmSivKey} keys and produces new instances of {@code
AesGcmSiv}.
java_src/src/main/java/com/google/crypto/tink/aead/AesGcmSivKeyManager.java