get environment parameter value from Java system properties or environment variables.
get environment parameter value from Java system properties or environment variables. To lookup java system properties the key is prefixed with "sdl.". To lookup environment variables the key is prefixed with "SDL_" and camelcase notation is converted to uppercase notation separated by "_". Java system properties have precedence over environment variables.
the name of the parameter in camelCase notation, starting with a lowercase letter.
check if running on windows os