How do you use participant filters mentioned in the Stash API documentation


I am trying to get a list of PRs by author using the Stash API. According to the documentation this is possible using participant filters, but I have not been able to find an example of the use of these filters in an API call. Does anyone have an example they can share. Here is the doc that mentions it.

The authenticated user must have REPO_READ permission for the specified repository to call this resource. Optionally clients can specify PR participant filters. Each filter has a mandatory {@code username.N} parameter, and the optional {@code role.N} and {@code approved.N} parameters.

{@code username.N} - the “root” of a single participant filter, where “N” is a natural number starting from 1. This allows clients to specify multiple participant filters, by providing consecutive filters as {@code username.1}, {@code username.2} etc. Note that the filters numbering has to start with 1 and be continuous for all filters to be processed. The total allowed number of participant filters is 10 and all filters exceeding that limit will be dropped.
{@code role.N}(optional) the role associated with {@code username.N}. This must be one of {@code AUTHOR}, {@code REVIEWER}, or{@code PARTICIPANT}
{@code approved.N}(optional) the approved status associated with {@code username.N}. That is whether {@code username.N} has approved the PR. Either {@code true}, or {@code false}