public URI httpsUri(SerializationFormat format) {
        return uri(HTTPS, format);
    }
Returns the HTTPS {@link URI} for the {@link Server}.

@return the absolute {@link URI} without a path.
@throws IllegalStateException if the {@link Server} is not started or
                              it did not open an HTTPS port.
junit5/src/main/java/com/linecorp/armeria/internal/testing/ServerRuleDelegate.java