vsphere/config.go
func (c *Config) restSessionFile() (string, error) {
	p, err := c.sessionFile()
	if err != nil {
		return "", err
	}
	return filepath.Join(c.RestSessionPath, p), nil
}
func (c *Config) restSessionFile() (string, error) {
	p, err := c.sessionFile()
	if err != nil {
		return "", err
	}
	return filepath.Join(c.RestSessionPath, p), nil
}
// restSessionFile is takes the session file name generated by sessionFile and
// then prefixes the REST client session path to it.