Tappx changes - Backward compatible change of version

[RodionOrets]

go repo PR: prebid/prebid-server#1777

[SerhiiNahornyi]

We have many concatenations in this method, can we use StringBuilder?

[RodionOrets]

@snahornyi Sure, but that would look somewhere like this:

...
StringBuilder urlBuilder = new StringBuilder()
                .append(endpointUrl)
                .append(host);

        if (!host.contains(endpoint)) {
            urlBuilder.append("/").append(endpoint);
        }

        urlBuilder.append("?tappxkey=").append(tappxkey);

        if (test != null && test == 0) {
            int t = (int) System.nanoTime();
            urlBuilder.append("&ts").append(t);
        }

        urlBuilder
                .append("&v=").append(VERSION)
                .append("&type_cnn=").append(TYPE_CNN);

        String url = urlBuilder.toString();
        try {
            HttpUtil.validateUrl(url);
        } catch (IllegalArgumentException e) {
            throw new PreBidException("Not valid url: " + url, e);
        }

        return url;
...

Which I think is less cleaner than "old" approach with url += ...
I'm trying to say it is not required here - we're not concatenating strings in a loop or something.
Since it's a simple concatenation, Java compiler will do the trick for us. At least for now I don't see any problem with += approach.
If not - let me know :)

[SerhiiNahornyi]

throw new PreBidException(String.format("Failed to build endpoint URL: %s", e.getMessage()));

[RodionOrets]

Done

[SerhiiNahornyi]

can be static

[RodionOrets]

And will be

[SerhiiNahornyi]

lets put all parameters creating together

uriBuilder.addParameter("tappxkey", tappxkey);
uriBuilder.addParameter("v", VERSION);
uriBuilder.addParameter("type_cnn", TYPE_CNN);

[RodionOrets]

Done

[rpanchyk]

Pls give reasonable names to variables.