Build is triggered when all thread are resolved

Jenkins and plugins versions report

Environment

```text Jenkins: 2.375.1 OS: Linux - 5.13.19-2-MANJARO Java: 17.0.1 - Eclipse Adoptium (OpenJDK 64-Bit Server VM) --- ant:487.vd79d090d4ea_e antisamy-markup-formatter:159.v25b_c67cd35fb_ apache-httpcomponents-client-4-api:4.5.14-150.v7a_b_9d17134a_5 bootstrap5-api:5.2.1-3 bouncycastle-api:2.28 branch-api:2.1092.vda_3c2a_a_f0c11 build-timeout:1.28 caffeine-api:3.1.6-115.vb_8b_b_328e59d8 checks-api:1.8.1 cloudbees-folder:6.815.v0dd5a_cb_40e0e commons-lang3-api:3.12.0-36.vd97de6465d5b_ commons-text-api:1.10.0-36.vc008c8fcda_7b_ credentials:1224.vc23ca_a_9a_2cb_0 credentials-binding:604.vb_64480b_c56ca_ display-url-api:2.3.7 durable-task:507.v050055d0cb_dd echarts-api:5.4.0-1 email-ext:2.97 font-awesome-api:6.2.1-1 git:5.0.2 git-client:4.2.0 github:1.37.1 github-api:1.314-431.v78d72a_3fe4c3 github-branch-source:1703.vd5a_2b_29c6cdc gitlab-api:5.2.0-86.v1ed41a_9cf486 gitlab-branch-source:659.va_685a_51fda_db_ gradle:2.7 handy-uri-templates-2-api:2.1.8-22.v77d5b_75e6953 instance-identity:142.v04572ca_5b_265 ionicons-api:56.v1b_1c8c49374e jackson2-api:2.15.1-344.v6eb_55303dc3e jakarta-activation-api:2.0.1-3 jakarta-mail-api:2.0.1-3 javax-activation-api:1.2.0-6 javax-mail-api:1.6.2-9 jaxb:2.3.8-1 jersey2-api:2.39.1-1 jjwt-api:0.11.5-77.v646c772fddb_0 jquery3-api:3.6.1-2 junit:1202.v79a_986785076 ldap:682.v7b_544c9d1512 mailer:448.v5b_97805e3767 matrix-auth:3.1.7 matrix-project:789.v57a_725b_63c79 mina-sshd-api-common:2.10.0-69.v28e3e36d18eb_ mina-sshd-api-core:2.10.0-69.v28e3e36d18eb_ okhttp-api:4.10.0-132.v7a_7b_91cef39c pam-auth:1.10 pipeline-build-step:491.v1fec530da_858 pipeline-github-lib:42.v0739460cda_c4 pipeline-graph-analysis:202.va_d268e64deb_3 pipeline-groovy-lib:656.va_a_ceeb_6ffb_f7 pipeline-input-step:468.va_5db_051498a_4 pipeline-milestone-step:111.v449306f708b_7 pipeline-model-api:2.2131.vb_9788088fdb_5 pipeline-model-definition:2.2131.vb_9788088fdb_5 pipeline-model-extensions:2.2131.vb_9788088fdb_5 pipeline-rest-api:2.32 pipeline-stage-step:305.ve96d0205c1c6 pipeline-stage-tags-metadata:2.2131.vb_9788088fdb_5 pipeline-stage-view:2.32 plain-credentials:143.v1b_df8b_d3b_e48 plugin-util-api:2.20.0 popper2-api:2.11.6-2 resource-disposer:0.22 scm-api:672.v64378a_b_20c60 script-security:1244.ve463715a_f89c snakeyaml-api:1.33-95.va_b_a_e3e47b_fa_4 ssh-credentials:305.v8f4381501156 ssh-slaves:2.877.v365f5eb_a_b_eec sshd:3.303.vefc7119b_ec23 structs:324.va_f5d6774f3a_d timestamper:1.25 token-macro:359.vb_cde11682e0c trilead-api:2.84.v72119de229b_7 variant:59.vf075fe829ccb workflow-aggregator:596.v8c21c963d92d workflow-api:1213.v646def1087f9 workflow-basic-steps:1017.vb_45b_302f0cea_ workflow-cps:3668.v1763b_b_6ccffd workflow-durable-task-step:1246.v5524618ea_097 workflow-job:1295.v395eb_7400005 workflow-multibranch:746.v05814d19c001 workflow-scm-step:408.v7d5b_135a_b_d49 workflow-step-api:639.v6eca_cd8c04a_a_ workflow-support:839.v35e2736cfd5c ws-cleanup:0.45 ```

What Operating System are you using (both controller, and any agents involved in the problem)?

linux

Reproduction steps

Create a project Organization Folder where gitlab is linked
- In the configuration select "Webhook Listener Conditions" -> [x] Ignore builds for non-code related MR updates
Create a MR
- This creates a MR build in Jenkins
Open some threads in the "changes" tab in GitLab
Push an other change on the target branch
- Otherwise the Webhook event will be processed, but you will see something like No changes detected: MR-1 (still at ab4cdf3ab68a29fca4cd9bcddeea81488562053a+e9a11a10a95b1b1bba186c5ed9988f9a27d9e210) after the line Met criteria
Resolve those threads

Expected Results

No build should be triggered, since resolving threads is not a code related MR update

Actual Results

A new build is triggered

In the page <Jenkins project>/indexing/events you see in the logs:

Checking merge requests..

Checking merge request !1
      ‘Jenkinsfile’ found
Met criteria
Changes detected: MR-1 (ab4cdf3ab68a29fca4cd9bcddeea81488562053a+8906c9ccd753c419445792a6c38d479494e325f3 → 5f22b0ba8be91b206175123a6026dc1fb33594be+8906c9ccd753c419445792a6c38d479494e325f3)
Scheduled build for branch: MR-1

1 merge requests were processed (query completed)
[Wed May 24 17:14:49 CEST 2023] Merge request !1 state:opened action:update in project jmini-test-group/jenkins-test changes:{
  "authorId" : null,
  "createdAt" : null,
  "updatedAt" : null,
  "updatedById" : null,
  "title" : null,
  "description" : null,
  "state" : null,
  "milestoneId" : null,
  "labels" : null,
  "assignees" : null,
  "totalTimeSpent" : null,
  "mergeStatus" : null
} UPDATED event from 34.74.90.77 ⇒ <jenkins server>/gitlab-webhook/post with timestamp Wed May 24 17:14:17 CEST 2023 processed in 2.2 sec

Anything else?

The webhook event contains following values:

    "blocking_discussions_resolved": true,
    "action": "update"

And it is sent probably because blocking_discussions_resolved transition from false to true but this is not modeled in the changes. --> I did not investigate further but to see this transition you might also need All discussions must be resolved according to issue #215589, but the behavior described here can be reproduced without the setting.

According to my analysis the code based on the changes object in the Webhook event is not the best:

https://github.com/jenkinsci/gitlab-branch-source-plugin/blob/d45c0f4c00428cd0d79ba15af87091708b4b58b8/src/main/java/io/jenkins/plugins/gitlabbranchsource/GitLabMergeRequestTrigger.java#L45-L76

I found this in the documentation:

The field object_attributes.oldrev is only available when there are actual code changes, like:

New code is pushed.

A suggestion is applied.

source: https://docs.gitlab.com/ee/user/project/integrations/webhook_events.html#merge-request-events

So for me the "Ignore builds for non-code related MR updates" should be based on the presence or absence of object_attributes.oldrev.

Which requires this change https://github.com/gitlab4j/gitlab4j-api/pull/980

jenkinsci / gitlab-branch-source-plugin