[JENKINS-37545] Manual installation of plugins in Jenkins2 does not follow detached plugins

Description

jenkins-2.16<br/>
ownership-0.5

Contributor guide

Tech stack

java

Domain

backenddevops

Issue type

bug

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

3

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

1-2 days

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

stale

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

mostly clear

Prerequisites

Basic Jenkins knowledgeJava programmingUnderstanding of plugin dependencies

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

60

Research direction

The issue describes a bug where manual plugin installation in Jenkins 2 does not handle detached plugins, causing an installation error when deploying the Ownership plugin which depends on code decoupled to the Matrix Auth plugin. To reproduce, look at the plugin installation mechanism in the Jenkins core, specifically the PluginManager class and its handling of dependencies. The maintainer should investigate how detached plugins are resolved during manual upload vs. automatic installation. The report mentions ownership 0.5 and Jenkins 2.16; the test environment and error screenshot are attached. Start by examining the code path for manual plugin installation, particularly the update center logic and how missing dependencies are handled. No linked PRs or assignees, so the issue is open for contribution.