POST only returning the branch of the last commit when multiple commits in the same branch

Hi.

I have a service that receives POST requests from bitbucket when a user pushes something.
The problem is that when the user do multiple commits (in the same branch) before pushing, the API only returns the branch of the last commit.

JSON example:
{
"repository":
{
[...]
},
"commits":
[
{
"node": "4307d459f62e",
"branch": null,
"raw_node": "4307d459f62e90ad34bfd1d0bbe34100234fb2d8",
[...]
},
{
"node": "7a69b1bdde69",
"branch": "nova-branch",
"raw_node": "7a69b1bdde69d1119661eb6173582bba4f80f653",
[...]
}
],
[...]
}