fun versionSelected(versions: List<String>, urlVersion: String?): String?
Look up specified in url version in available versions.
If requested version is listed in available versions list then it will be returned. Else if there is no requested version then will be returned first version from available list if list is not empty. In the end if all above returned false will be returned null.
versions - a list of available versions;
urlVersion - version from url param.
Return
version from available list if there is such version, 'null' otherwise.