src/main/java/com/coinbase/api/CoinbaseBuilder.java
public CoinbaseBuilder withApiKey(String api_key, String api_secret) {
    	this.api_key = api_key;
    	this.api_secret = api_secret;
    	return this;
    }
public CoinbaseBuilder withApiKey(String api_key, String api_secret) {
    	this.api_key = api_key;
    	this.api_secret = api_secret;
    	return this;
    }
Specify the HMAC api key and secret to be used for authenticated requests

Having more than one client with the same api/secret globally is unsupported
and will result in sporadic auth errors as the nonce is calculated from the system time.

@param api_key the HMAC API Key
@param api_secret the HMAC API Secret

@return this CoinbaseBuilder object