@Nullable
    public static NameID getNameId(Response response, SamlNameIdFormat expectedFormat) {
        return getNameId(response, nameId -> nameId.getFormat().equals(expectedFormat.urn()));
    }
Returns a {@link NameID} that its name format equals to the specified {@code expectedFormat},
from the {@link Response}.
saml/src/main/java/com/linecorp/armeria/server/saml/SamlUtil.java