Update "Date" header correctly

HttpResponse headers are multi-map, so we need to replace previous Date header when it is updated.
Also I changed the response to use TimeSource so it can be tested easier with less chance of random failure.

[johnfargo, 2010-08-04 20:23:02]

http://codereview.appspot.com/1888045/diff/1/3
File
java/gadgets/src/main/java/org/apache/shindig/gadgets/http/HttpResponse.java
(right):

http://codereview.appspot.com/1888045/diff/1/3#newcode157
java/gadgets/src/main/java/org/apache/shindig/gadgets/http/HttpResponse.java:157:
}
We might want to set, and then use, HttpUtil's TimeSource, since its methods
(specifically setCachingHeaders) use it as well. Doing so avoids duplicate
marking of classes for static injection and simplifies tests (somewhat :)).

[zhoresh, 2010-08-04 21:54:08]

Update to use HttpUtil time source (good catch John)

[johnfargo, 2010-08-04 22:03:42]

LGTM

http://codereview.appspot.com/1888045/diff/6001/7003
File
java/gadgets/src/main/java/org/apache/shindig/gadgets/http/HttpResponse.java
(right):

http://codereview.appspot.com/1888045/diff/6001/7003#newcode368
java/gadgets/src/main/java/org/apache/shindig/gadgets/http/HttpResponse.java:368:
return expiration - HttpUtil.getTimeSource().currentTimeMillis();
feel free to introduce your own getter in this class, which just delegates to
HttpUtil, for encapsulation purposes.

[zhoresh, 2010-08-04 22:10:33]

On 2010/08/04 22:03:42, johnfargo wrote:
> LGTM
> 
> http://codereview.appspot.com/1888045/diff/6001/7003
> File
> java/gadgets/src/main/java/org/apache/shindig/gadgets/http/HttpResponse.java
> (right):
> 
> http://codereview.appspot.com/1888045/diff/6001/7003#newcode368
>
java/gadgets/src/main/java/org/apache/shindig/gadgets/http/HttpResponse.java:368:
> return expiration - HttpUtil.getTimeSource().currentTimeMillis();
> feel free to introduce your own getter in this class, which just delegates to
> HttpUtil, for encapsulation purposes.

Done, and committed.
Thanks!