I don't have enough time to diagnose the problem for now, and will write notes that may help you to debug.

It looks like that Jenkins for the test launched in the temporary directory misses source codes and compiled objects.
As far as I know, Jenkins for the test looks up sources and binaries in this way:

• the.hpl is put to the plugin dir for Jenkins for test.
  • It should be a path like C:\Users\myusername\AppData\Local\Temp\Jetty_0_0_0_0_0_jenkins.for.test___.bj8wp3\webapp\WEB-INF\plugins
  • This directory is deleted after tests, and you need to add Thread.sleep(big number) in test codes.
• In that file, paths to your target/classes are written.
• Also in target/classes/META-INF/annotations/hudson.Extensions, classes annotated with @Extension is written (in binary formats).

and

• IDE may cause the problem. Please try run the maven command on a console.
• Older maven might fix the problem.
• Using the latest maven-hpi-plugin may fix the problem. But I don't know how to do that as I'm not good at maven.
• Comparing with logs on Jenkins may help the debug
  • https://jenkins.ci.cloudbees.com/job/plugins/job/extensible-choice-parameter-plugin/46/

Could not reproduce the issue even with maven-3.3.9.

My environment:

[INFO] Maven Version: 3.1.1
[INFO] JDK Version: 1.7.0_79 normalized as: 1.7.0-79
[INFO] OS Info: Arch: amd64 Family: windows Name: windows 8.1 Version: 6.3

[INFO] Maven Version: 3.3.9
[INFO] JDK Version: 1.7.0_79 normalized as: 1.7.0-79
[INFO] OS Info: Arch: amd64 Family: windows Name: windows 8.1 Version: 6.3

As commented before, I cannot reproduce the problem.
It looks a problem of your environment.
extensible-choice now uses plugin pom 2.11, and it may fix the problem in your environment. Please try that.