The CSPAPIToken option can change in unexpected ways

[keep94]

The CSPAPIToken option can change in unexpected ways. Ideally an option should be immutable once created. Consider this code:

cspOptions := []CSPOption{CSPOrgId("orgId")}
option := CSAPIToken("tokenName", cspOptions...)
sender := NewSender(wavefrontURL, option)
cspOptions[0] = CSPOrgId("aDifferentOrgId")
// Oops, anotherSender will use "aDifferentOrgId" because option changed as a side effect
anotherSender := NewSender(wavefrontURL, option)

Solution, the CSPAPIToken() function should take a defensive copy of the slice of CSPOptions passed in. Then it should use that defensive copy in the returned function. This would be enough:

func CSPAPIToken(cspAPIToken string, options ...CSPOption) Option {
        optionsCopy := append([]CSPOption(nil), options...)
	return func(c *configuration) {
		cspTokenAuth := auth.CSPAPIToken{
			Token:   cspAPIToken,
			BaseURL: defaultCSPBaseURL,
		}
		for _, option := range optionsCopy {
			option(&cspTokenAuth)
		}
		c.Authentication = cspTokenAuth
	}
}