In TeamCity, trigger build with 2 VCS roots with 2 custom revisions using REST API - rest

Question

looking for collective wisdom on this problem I am tackling.
I need to trigger build using REST API on TeamCity. The build configuration has 2 VCS roots and I need to pass specific revision for both of them. In documentation, I found example for single VCS, but I am stuck on setting revisions for both of them.
I am trying to set up something like this:
{
"buildType": {
"id": "ExampleConfiguration"
},
"defaultBranch": "false",
"lastChanges": {
"change": [
{
"locator": "combination of locators that will set VCS 1 - branch + revision"
},
{
"locator": "combination of locators that will set VCS 2 - branch + revision"
}
]
}
}
In principle, I am simulating execution of the build, where both revisions are manually set - this is possible in the UI.
https://www.jetbrains.com/help/teamcity/rest/start-and-cancel-builds.html#Advanced+Build+Run
TC version: 2022.04.3 (build 108706)
Edit:
I was able to detect the changes and resolve their id on both VCS roots. For the changes field in the body I can now use locator of the form {"id": 123456}. But another obstacle on the road, if I specify pair of these changes:
"lastChanges": { "change": [ {"id": 1}, {"id": 2} ] }
I get error
Responding with error, status code: 400 (Bad Request).
Details: jetbrains.buildServer.server.rest.errors.BadRequestException: Several non-personal changes are submitted, only one can be present
Invalid request. Please check the request URL and data are correct.
Same build with the exact revisions is possible to trigger manually from TC UI.

Answer 1

Finally resolved it. The way to go is to use revisions instead of lastChanges. To pass revisions for 2 VCS roots together with branch names, use this:
"revisions": {
"revision": [
{
"vcs-root-instance": {
"id": "111"
},
"vcsBranchName": "branch-name-111",
"version": "rev_on_vcs_111"
},
{
"vcs-root-instance": {
"id": "222"
},
"vcsBranchName": "branch-name-222",
"version": "rev_on_vcs_222"
}
]
}
To resolve VCS root instance id, use API call /app/rest/vcs-root-instances/vcsRoot:(id:(Project_Vcs_Root))"