private function transformKey($key)
    {
        $regEx = '/(?#! splitCamelCase Rev:20140412)
            # Split camelCase "words". Two global alternatives. Either g1of2:
              (?<=[a-z])      # Position is after a lowercase,
              (?=[A-Z])       # and before an uppercase letter.
            | (?<=[A-Z])      # Or g2of2; Position is after uppercase,
              (?=[A-Z][a-z])  # and before upper-then-lower case.
            /x';

        $words   = preg_split($regEx, $key);
        $envName = implode('_', $words);
        $envName = str_replace(['.', '_', '-'], '_', $envName);
        $envName = strtoupper($envName);

        return $envName;
    }