Allow QueryMapEncoder accept null value

[quaff]

	@GetMapping
	public Paged<User> list(int page, int size, @QueryMap User user);

Currently feign doesn't accept null user

Paged<User> paged = userClient.list(1, 10, new User()); // query map will include primitive type default values which is unexpected
Paged<User> paged = userClient.list(1, 10, null); // will leave query map empty

[quaff]

Closed without any comment?

[velo]

I batch closed all old PRs that I either had conflicts or the build didn't pass. If you manage to re-submit it in the next days, I can review and get it merged asap

[velo]

seems this one is a broken build

[quaff]

It seems formatting issue

The following files have formatting changes:
+ git status --porcelain
 M core/src/test/java/feign/querymap/BeanQueryMapEncoderTest.java
 M core/src/test/java/feign/querymap/FieldQueryMapEncoderTest.java

Do you think this improvement is reasonable?