What is the meaning of the "changes" field in a webhook push event?

[momocow]

From the document, it tells me that

The details of the push, which includes the changes property. This property contains an array with all the references that the push updated and the following properties...  

But I still cannot understand what is a reference?

I've tested to make multiple commits in a single push and the changes field always contains a single element. (Multiple commits can be found in "commits" field under changes field)

What I want to know is that when will the changes field contains more than one element?

(I only care about push event)

Thanks if someone can provide an answer!

[Kirill 'kkm' Katsnelson]

Git documentation on references. Basically, for your purposes, it's either a branch or a tag. The 'type:' field in the message is either 'branch' or 'tag', and the 'name:' is a single word, like 'master' or 'v15.1', without the prefix (in Git proper, this would be 'refs/heads/master' and 'refs/tags/v15.1').

There is an array in the hook message, because a single Git push may send multiple branches and tags at once (take heed of the command syntax: it ends in '<refspec>…'. Even when you do just 'git push' with no arguments, depending on the local repo configuration settings, it may send along all tags added locally, or even push many branches at once.