maven-enforcer-plugin issue while creating org.jenkins-ci.plugins in eclipse

Question

I try to get a minimal empty jenkins plugin to compile and show in a jetty jenkins.

I created a new Java Project and made it into a maven project. Right Click -> Configure -> Into Maven.

My problem stems from the Parent.

Group Id: org.jenkins-ci.plugins 
Artifact Id: plugin
Version: 3.9

When I execute the Goal RunAs -> Maven -> Install I get an error. The error string contains:

maven-enforcer-plugin:3.0.0-M1:enforce failed: Unknown JDK version given. Should be something like "1.7"

I Installed multiple Java Versions in the machine so I should have some to choose from. I tried to set a deifferent JRE dependency in the Project Propererties with no effect.

A bit further up there is a relevant output:

[INFO] --- maven-enforcer-plugin:3.0.0-M1:display-info (display-info) @ ManualTestingMapper ---
[INFO] Maven Version: 3.3.9
[INFO] JDK Version: 1.8.0_162 normalized as: 1.8.0-162
[INFO] OS Info: Arch: amd64 Family: windows Name: windows 7 Version: 6.1
[INFO] 
[INFO] --- maven-enforcer-plugin:3.0.0-M1:enforce (display-info) @ ManualTestingMapper ---

My Windows environment has JAVA_HOME=c:\Program Files (x86)\Java\jre8u152 and the PATH also points in that general direction.

How does one fix this in eclipse? I would need to change the JDK version on a per project level. I can not find anything useful using google - those were all dead ends fir me.

EDIT: I should mention that changing the Project Facets to Java 1.7 gives the enforcer output:

[INFO] --- maven-enforcer-plugin:3.0.0-M1:display-info (display-info) @ ManualTestingMapper ---
[INFO] Maven Version: 3.3.9
[INFO] JDK Version: 1.7.0_80 normalized as: 1.7.0-80
[INFO] OS Info: Arch: amd64 Family: windows Name: windows 7 Version: 6.1
[INFO] 
[INFO] --- maven-enforcer-plugin:3.0.0-M1:enforce (display-info) @ ManualTestingMapper ---

The error about needing JDK 1.7 is still the same though.

EDIT: Here is my POM, I updated the IDs to something neutral.

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>SOGrouID</groupId>
  <artifactId>SOArtifactID</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>SOName</name>
  <description>SOName is a Stackoverflow Example.</description>
  <parent>
    <groupId>org.jenkins-ci.plugins</groupId>
    <artifactId>plugin</artifactId>
    <version>3.9</version>
  </parent>
</project>

The parent POM contains

<requireJavaVersion>
<version>[1.8.0,)</version>
</requireJavaVersion>

which raises more questions than it answers. The whole parent POM can be inspected on github.

EDIT: Running the maven goal Install -X gives the exception type:

java.lang.IllegalArgumentException: Unknown JDK version given. Should be something like "1.7"

I guess "1.7" could be meant as a format example. If that is so then the plugin may be presented with an incomprehensible format string of sorts?

Answer 1

Thanks to @Kai who pointed me towards the parent POM. There are a bunch of properties that are marked with you-must-override. One of them is

<java.level>you-must-override-the-java.level-property</java.level>

The IllegalArgumentException comes from the string that was given.

Overriding that property in the pom removes the issue.

  <properties>
    <java.level>8</java.level>
  </properties>  

Answer 2

The problem isn't related to your installed Java version. Open the pom.xml and look for the maven-enforcer-plugin. I guess the configuration is wrong here, there should be something like:

<requireJavaVersion>
  <version>1.7</version>
</requireJavaVersion>