String computeApiKeyHash(final String apiKeyStr) {
        return computeApiKeyHash(apiKeyStr, HashAlgorithm.DEFAULT);
    }
Fetch the verified {@link UserIdentity} for the passed API key.
If the hash of the API key matches one in the database and that key is enabled
and not expired then the {@link UserIdentity} will be returned, else an empty {@link Optional}
is returned.
stroom-security/stroom-security-impl/src/main/java/stroom/security/impl/apikey/ApiKeyService.java