private static VirtualHost setSslContextIfAbsent(VirtualHost h,
                                                     @Nullable SslContext defaultSslContext) {
        if (h.sslContext() != null || defaultSslContext == null) {
            return h;
        }
        return h.withNewSslContext(defaultSslContext);
    }
Returns a list of {@link ServerPort}s which consists of distinct port numbers except for the port
{@code 0}. If there are the same port numbers with different {@link SessionProtocol}s,
their {@link SessionProtocol}s will be merged into a single {@link ServerPort} instance.
The returned list is sorted as the same order of the specified {@code ports}.
core/src/main/java/com/linecorp/armeria/server/ServerBuilder.java