public static final KeyTemplate hkdfSha256Template() {
    return exceptionIsBug(
        () ->
            KeyTemplate.createFrom(
                HkdfPrfParameters.builder()
                    .setKeySizeBytes(32)
                    .setHashType(HkdfPrfParameters.HashType.SHA256)
                    .build()));
  }
Generates a {@link KeyTemplate} for HKDF-PRF keys with the following parameters.

<ul>
  <li>Hash function: SHA256
  <li>HMAC key size: 32 bytes
  <li>Salt: empty
</ul>
java_src/src/main/java/com/google/crypto/tink/prf/HkdfPrfKeyManager.java