Numeric subdomain strings for maptile providers

Just a warning note. If you are using a maptile provider like HERE.com that requires a subdomain string like:

"subdomains": "1234"

you cannot put 'subdomains' => '1234' in clientOptions. The code will actually turn that into:

"subdomains": 1234 which fails.

Instead, use the alternative array format: 'subdomains' => ['1', '2', '3', '4'] which works