Fix Response Charset to UTF-8.

[kikutaro]

patch for issue #6

[thinkingserious]

This is awesome, thanks! We have this on our backlog to be merged.

Also, please email us at dx@sendgrid.com with your T-shirt size and mailing address so we can send you some swag :)

[kikutaro]

Hi @thinkingserious , I sent email :) Thanks!

[thinkingserious]

Hello @kikutaro,

I ran into an issue when trying to run the Example. On this line, I get:

Exception in thread "main" java.lang.IllegalArgumentException: Entity may not be null
    at org.apache.http.util.Args.notNull(Args.java:54)
    at org.apache.http.util.EntityUtils.toString(EntityUtils.java:214)
    at com.sendgrid.Client.getResponse(Client.java:138)
    at com.sendgrid.Client.delete(Client.java:344)
    at com.sendgrid.Client.api(Client.java:375)
    at Example.main(Example.java:109)

I'm thinking we just need a null check before we call EntityUtils.

[kikutaro]

Oh, okay. Sorry for that I didn't check the example. I only focus test code.
I'll check the case soon. Thanks.

[kikutaro]

Hi @thinkingserious,

I added null check. Thanks.

[thinkingserious]

Awesome, thanks!

[thinkingserious]

@kikutaro,

Could you please update your branch against the latest version? https://github.com/sendgrid/java-http-client/releases/tag/v2.3.3

I'd like to merge your branch next. Thanks!

[kikutaro]

I tried it. Sorry that I'm pretty new this pattern merge for me...
If you have any issue on my pull request, please let me know. Thanks.