public static final KeyTemplate hmacSha512HalfDigestTemplate() {
    return exceptionIsBug(
        () ->
            KeyTemplate.createFrom(
                HmacParameters.builder()
                    .setKeySizeBytes(64)
                    .setTagSizeBytes(32)
                    .setHashType(HmacParameters.HashType.SHA512)
                    .setVariant(HmacParameters.Variant.TINK)
                    .build()));
  }
@return A {@link KeyTemplate} that generates new instances of HMAC keys with the following
    parameters:
    <ul>
      <li>Key size: 64 bytes
      <li>Tag size: 32 bytes
      <li>Hash function: SHA512
      <li>Prefix type: {@link KeyTemplate.OutputPrefixType#TINK}
    </ul>
java_src/src/main/java/com/google/crypto/tink/mac/HmacKeyManager.java