public static KeyData createAesGcmHkdfStreamingKeyData(
      byte[] keyValue, int derivedKeySize, int ciphertextSegmentSize) throws Exception {
    AesGcmHkdfStreamingParams keyParams =
        AesGcmHkdfStreamingParams.newBuilder()
            .setCiphertextSegmentSize(ciphertextSegmentSize)
            .setDerivedKeySize(derivedKeySize)
            .setHkdfHashType(HashType.SHA256)
            .build();
    AesGcmHkdfStreamingKey keyProto =
        AesGcmHkdfStreamingKey.newBuilder()
            .setVersion(0)
            .setKeyValue(ByteString.copyFrom(keyValue))
            .setParams(keyParams)
            .build();
    return createKeyData(
        keyProto,
        StreamingAeadConfig.AES_GCM_HKDF_STREAMINGAEAD_TYPE_URL,
        KeyData.KeyMaterialType.SYMMETRIC);
  }
@return a {@code KeyData} containing a {@code AesGcmHkdfStreamingKey}.
java_src/src/main/java/com/google/crypto/tink/testing/TestUtil.java