merge-request caused-by event displays partial json payload.

[madelaney]

Jenkins and plugins versions report

Environment

Jenkins: 2.401.1
OS: Linux - 5.15.0-1029-azure
Java: 11.0.19 - Ubuntu (OpenJDK 64-Bit Server VM)
---
Office-365-Connector:4.18.0
ace-editor:1.1
analysis-model-api:11.3.0
ansicolor:1.0.2
ant:487.vd79d090d4ea_e
antisamy-markup-formatter:159.v25b_c67cd35fb_
apache-httpcomponents-client-4-api:4.5.14-150.v7a_b_9d17134a_5
artifactory:3.18.3
atlassian-jira-software-cloud:2.0.7
audit-trail:333.vb_e1b_b_0f1238c
authentication-tokens:1.53.v1c90fd9191a_b_
aws-credentials:191.vcb_f183ce58b_9
aws-java-sdk-ec2:1.12.481-392.v8b_291cfcda_09
aws-java-sdk-minimal:1.12.481-392.v8b_291cfcda_09
azure-ad:349.vc02b_a_0b_142a_8
azure-credentials:254.v64da_8176c83a
azure-sdk:132.v62b_48eb_6f32f
azure-vm-agents:859.v7213476e4fea_
badge:1.9.1
basic-branch-build-strategies:71.vc1421f89888e
bitbucket:223.vd12f2bca5430
blueocean:1.27.4
blueocean-autofavorite:1.2.5
blueocean-bitbucket-pipeline:1.27.4
blueocean-commons:1.27.4
blueocean-config:1.27.4
blueocean-core-js:1.27.4
blueocean-dashboard:1.27.4
blueocean-display-url:2.4.2
blueocean-events:1.27.4
blueocean-git-pipeline:1.27.4
blueocean-github-pipeline:1.27.4
blueocean-i18n:1.27.4
blueocean-jwt:1.27.4
blueocean-personalization:1.27.4
blueocean-pipeline-api-impl:1.27.4
blueocean-pipeline-editor:1.27.4
blueocean-pipeline-scm-api:1.27.4
blueocean-rest:1.27.4
blueocean-rest-impl:1.27.4
blueocean-web:1.27.4
bootstrap5-api:5.3.0-1
bouncycastle-api:2.28
branch-api:2.1109.vdf225489a_16d
build-monitor-plugin:1.14-717.v3efcdffe8d58
build-time-blame:70.v5031def3c2e3-2.1.0
build-timeout:1.31
build-timestamp:1.0.3
buildtriggerbadge:251.vdf6ef853f3f5
caffeine-api:3.1.6-115.vb_8b_b_328e59d8
change-assembly-version-plugin:1.10
checks-api:2.0.0
claim:516.v36293563731d
cloud-stats:267.v577e3742c282
cloudbees-bitbucket-branch-source:809.vc1d904b_30426
cloudbees-folder:6.815.v0dd5a_cb_40e0e
cobertura:1.17
code-coverage-api:4.7.0
command-launcher:100.v2f6722292ee8
commons-httpclient3-api:3.1-3
commons-lang3-api:3.12.0-36.vd97de6465d5b_
commons-text-api:1.10.0-36.vc008c8fcda_7b_
config-file-provider:938.ve2b_8a_591c596
configuration-as-code:1647.ve39ca_b_829b_42
copyartifact:705.v5295cffec284
credentials:1254.vb_96f366e7b_a_d
credentials-binding:604.vb_64480b_c56ca_
custom-tools-plugin:0.8
dark-theme:336.v02165cd8c2ee
dashboard-view:2.487.vcf0ff9008a_c0
data-tables-api:1.13.4-2
datadog:5.4.1
display-url-api:2.3.7
docker-commons:419.v8e3cd84ef49c
docker-workflow:563.vd5d2e5c4007f
dropdown-viewstabbar-plugin:1.7
dtkit-api:3.0.2
durable-task:507.v050055d0cb_dd
echarts-api:5.4.0-5
email-ext:2.99
emailext-template:1.5
embeddable-build-status:385.vc95f94e91fb_3
extended-choice-parameter:373.v1a_ecea_fdf2a_a_
extended-read-permission:53.v6499940139e5
external-monitor-job:203.v683c09d993b_9
favorite:2.4.2
font-awesome-api:6.4.0-1
forensics-api:2.3.0
git:5.1.0
git-changelog:3.30
git-client:4.4.0
git-forensics:2.0.0
github:1.37.1
github-api:1.314-431.v78d72a_3fe4c3
github-branch-source:1728.v859147241f49
gitlab-api:5.3.0-88.vf8787b_92d679
gitlab-branch-source:663.v2602c3e6376d
gitlab-plugin:1.7.14
gradle:2.8
groovy:453.vcdb_a_c5c99890
h2-api:11.1.4.199-12.v9f4244395f7a_
handlebars:3.0.8
handy-uri-templates-2-api:2.1.8-22.v77d5b_75e6953
hashicorp-vault-pipeline:1.4
hashicorp-vault-plugin:360.v0a_1c04cf807d
htmlpublisher:1.31
implied-labels:228.v63b_3f8443d4e
instance-identity:173.va_37c494ec4e5
ionicons-api:56.v1b_1c8c49374e
ivy:2.5
jackson2-api:2.15.2-350.v0c2f3f8fc595
jakarta-activation-api:2.0.1-3
jakarta-mail-api:2.0.1-3
javadoc:233.vdc1a_ec702cff
javax-activation-api:1.2.0-6
javax-mail-api:1.6.2-9
jaxb:2.3.8-1
jdk-tool:66.vd8fa_64ee91b_d
jenkins-design-language:1.27.4
jersey2-api:2.39.1-2
jfrog:1.4.0
jira:3.10
jjwt-api:0.11.5-77.v646c772fddb_0
jnr-posix-api:3.1.17-1
jobConfigHistory:1212.vd4470d08ff12
jquery:1.12.4-1
jquery3-api:3.7.0-1
jsch:0.2.8-65.v052c39de79b_2
junit:1207.va_09d5100410f
kubernetes:3937.vd7b_82db_e347b_
kubernetes-client-api:6.4.1-215.v2ed17097a_8e9
kubernetes-credentials:0.10.0
label-linked-jobs:6.0.1
ldap:682.v7b_544c9d1512
lockable-resources:1166.v7ef984f72fe2
mailer:457.v3f72cb_e015e5
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matrix-project:789.v57a_725b_63c79
maven-plugin:3.22
mercurial:1260.vdfb_723cdcc81
metrics:4.2.18-439.v86a_20b_a_8318b_
mina-sshd-api-common:2.10.0-69.v28e3e36d18eb_
mina-sshd-api-core:2.10.0-69.v28e3e36d18eb_
modernstatus:1.3
momentjs:1.1.1
monitoring:1.94.1
msbuild:1.30
nodejs:1.6.0
nunit:394.v65c09a_8408b_a_
okhttp-api:4.11.0-145.vcb_8de402ef81
pam-auth:1.10
parameterized-scheduler:1.2
parameterized-trigger:2.45
pipeline-aggregator-view:1.15
pipeline-build-step:496.v2449a_9a_221f2
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-maven:1298.v43b_82f220a_e9
pipeline-milestone-step:111.v449306f708b_7
pipeline-model-api:2.2141.v5402e818a_779
pipeline-model-definition:2.2141.v5402e818a_779
pipeline-model-extensions:2.2141.v5402e818a_779
pipeline-npm:95.v5213efa_9585f
pipeline-rest-api:2.32
pipeline-stage-step:305.ve96d0205c1c6
pipeline-stage-tags-metadata:2.2141.v5402e818a_779
pipeline-stage-view:2.32
pipeline-utility-steps:2.15.4
plain-credentials:143.v1b_df8b_d3b_e48
plugin-util-api:3.3.0
popper2-api:2.11.6-2
postgresql-api:42.3.3
prism-api:1.29.0-7
project-stats-plugin:23.v47fee1f77b_84
pubsub-light:1.17
resource-disposer:0.22
role-strategy:633.v836e5b_3e80a_5
scm-api:676.v886669a_199a_a_
script-security:1251.vfe552ed55f8d
simple-theme-plugin:160.vb_76454b_67900
slack:664.vc9a_90f8b_c24a_
snakeyaml-api:1.33-95.va_b_a_e3e47b_fa_4
sse-gateway:1.26
ssh-credentials:305.v8f4381501156
sshd:3.303.vefc7119b_ec23
structs:324.va_f5d6774f3a_d
swarm:3.40
terraform:1.0.10
theme-manager:193.vcef22f6c5f2b_
timestamper:1.25
token-macro:359.vb_cde11682e0c
trilead-api:2.84.v72119de229b_7
variant:59.vf075fe829ccb
view-job-filters:364.v48a_33389553d
warnings-ng:10.2.0
windows-slaves:1.8.1
workflow-aggregator:596.v8c21c963d92d
workflow-api:1215.v2b_ee3e1b_dd39
workflow-basic-steps:1017.vb_45b_302f0cea_
workflow-cps:3691.v28b_14c465a_b_b_
workflow-durable-task-step:1247.v7f9dfea_b_4fd0
workflow-job:1308.v58d48a_763b_31
workflow-multibranch:756.v891d88f2cd46
workflow-scm-step:415.v434365564324
workflow-step-api:639.v6eca_cd8c04a_a_
workflow-support:839.v35e2736cfd5c
ws-cleanup:0.45
xunit:3.1.2

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

Ubuntu Linux (20.04), either in docker or in Azure.

Reproduction steps

1. Create repo in gitlab
2. Create analog job in jenkins
3. Create branch and make changes.
4. Open a merge-request
5. Make a code change to said branch / merge request
6. See the build even reason in Jenkins as something like

Expected Results

The title of the merge-request build would be something like:
Triggered by GitLab Merge Request #1: project-xxxxx => main

Actual Results

The title of the merge-request build is:

[Merge request !1 state:opened action:update changes:{ "authorId" : null, "createdAt" : null, "updatedAt" : { "previous" : "2023-06-16T12:31:07Z", "current" : "2023-06-16T14:11:28Z" }, "updatedById" : null, "title" : null, "description" : null, "state" : null, "milestoneId" : null, "labels" : null, "assignees" : null, "totalTimeSpent" : null, "mergeStatus" : null, "reviewers" : null } at 10:11:29 AM on Jun 16, 2023](https://jenkins.company.site/terraform-module/indexing/events)

Anything else?

This is Gitlab 16.0.1 (debian package)