This fixes a bug where no checkpoints would produce a `null` response
instead of an empty array:

```
$ docker run -d --name foo nginx:alpine
17fbeff7185733f101c38cb8208359dd0ef141116a1345da2d3c3f58c11f3e14

$ curl --unix-socket /var/run/docker.sock http://local/containers/foo/checkpoints
null
```

With this patch, this becomes:
```
$ curl --unix-socket /var/run/docker.sock http://local/containers/foo/checkpoints
[]
```

Signed-off-by: Paweł Gronowski <[email protected]>
(cherry picked from commit 646e068)
Signed-off-by: Paweł Gronowski <[email protected]>

[28.x backport] api/checkpoint: Don't return null if no checkpoints

This field was no longer used since Docker 1.11 (API version 1.23)
through [aee260d] and [engine-api@9a9e468] but kept and deprecated
in [engine-api@167efc7], however the docs still used it in an example.

Signed-off-by: Sebastiaan van Stijn <[email protected]>
(cherry picked from commit 08d014c)
Signed-off-by: Sebastiaan van Stijn <[email protected]>

[28.x backport] api/docs: remove email field from example auth

Commit 380ded6 restored a now-unused endpoint count to the
store, so that when the daemon is downgraded it exists for
the old code to find.

But, on network deletion, the endpoint count was not loaded
from the store - so the delete code saw the wrong "index",
and logged a warning before deleting it anyway.

Use DeleteObject instead of DeleteObjectAtomic, so the old
index isn't checked.

Signed-off-by: Rob Murray <[email protected]>
(cherry picked from commit 94bcf89)
Signed-off-by: Sebastiaan van Stijn <[email protected]>

[28.x backport] Eliminate warning about endpoint count store delete

Starting with kernel v6.12, kernel memory TCP accounting is deprecated for cgroups v1.
Note: kernel memory TCP accounting is not supported by cgroups v2.

See torvalds/linux@d046ff4

Signed-off-by: Austin Vazquez <[email protected]>
(cherry picked from commit fb2f811)
Signed-off-by: Austin Vazquez <[email protected]>
Signed-off-by: Sebastiaan van Stijn <[email protected]>

…rnel-memocy-tcp-to-28.x

[28.x backport] api: deprecate `KernelMemoryTCP` support

The `VirtualSize` field was deprecated in [1261fe6], and omitted / removed
in API v1.44 in [913b0f5]. We should not document the field as part of
those API versions as it no longer exists for those.

[1261fe6]: 1261fe6
[913b0f5]: 913b0f5

Signed-off-by: Sebastiaan van Stijn <[email protected]>
(cherry picked from commit 51cbd2e)
Signed-off-by: Sebastiaan van Stijn <[email protected]>

…ated_virtualsize

[28.x backport] api: swagger: remove VirtualSize fields for API > v1.43

Signed-off-by: Paweł Gronowski <[email protected]>
(cherry picked from commit 3f3bbe4)
Signed-off-by: Paweł Gronowski <[email protected]>

[28.x backport] vendor: github.com/moby/buildkit v0.25.0