--threads 1 (or -T 1) stucks the plugin

[blacelle]

For an unknown reason, executing this plugin with : '--thread 1' stuck the build.

I execute:

mvn org.eluder.coveralls:coveralls-maven-plugin:report --thread 1 -X

It get me into:

[INFO] last-module-of-my-reactor                                                          [jar]
[DEBUG] === REACTOR BUILD PLAN ================================================
[DEBUG] Project: io.mitrust:aggregator-mitrust:pom:34.0-SNAPSHOT
[DEBUG] Tasks:   [org.eluder.coveralls:coveralls-maven-plugin:report]
[DEBUG] Style:   Aggregating
[DEBUG] =======================================================================

The only relevant stack in jstack is:

"main" #1 prio=5 os_prio=0 cpu=1662.12ms elapsed=11.71s tid=0x00007f7450015800 nid=0xfe1 waiting on condition  [0x00007f7457e26000]
   java.lang.Thread.State: WAITING (parking)
	at jdk.internal.misc.Unsafe.park(java.base@11.0.8/Native Method)
	- parking to wait for  <0x00000000e7712060> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
	at java.util.concurrent.locks.LockSupport.park(java.base@11.0.8/LockSupport.java:194)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(java.base@11.0.8/AbstractQueuedSynchronizer.java:2081)
	at java.util.concurrent.LinkedBlockingQueue.take(java.base@11.0.8/LinkedBlockingQueue.java:433)
	at java.util.concurrent.ExecutorCompletionService.take(java.base@11.0.8/ExecutorCompletionService.java:200)
	at org.apache.maven.lifecycle.internal.builder.multithreaded.MultiThreadedBuilder.multiThreadedProjectTaskSegmentBuild(MultiThreadedBuilder.java:145)
	at org.apache.maven.lifecycle.internal.builder.multithreaded.MultiThreadedBuilder.build(MultiThreadedBuilder.java:103)
	at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:305)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:192)
	at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:105)
	at org.apache.maven.cli.MavenCli.execute(MavenCli.java:957)
	at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:289)
	at org.apache.maven.cli.MavenCli.main(MavenCli.java:193)
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(java.base@11.0.8/Native Method)
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(java.base@11.0.8/NativeMethodAccessorImpl.java:62)
	at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(java.base@11.0.8/DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(java.base@11.0.8/Method.java:566)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:282)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:225)
	at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:406)
	at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:347)
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(java.base@11.0.8/Native Method)
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(java.base@11.0.8/NativeMethodAccessorImpl.java:62)
	at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(java.base@11.0.8/DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(java.base@11.0.8/Method.java:566)
	at org.apache.maven.wrapper.BootstrapMainStarter.start(BootstrapMainStarter.java:39)
	at org.apache.maven.wrapper.WrapperExecutor.execute(WrapperExecutor.java:122)
	at org.apache.maven.wrapper.MavenWrapperMain.main(MavenWrapperMain.java:61)