[MRRESOURCES-101] NPE - Error rendering velocity resource

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.5
• Fix Version/s: 1.6.0
• Flags: Patch
• Assignee: Unassigned
• Reporter: Daniel Klessing
• Created: 06/Apr/17 15:10
• Updated: 16/Sep/18 16:53
• Resolved: 16/Sep/18 16:53

Description

We noticed that occasionally the maven-remote-resources-plugin kills our build as a NPE with the message "Error rendering velocity resource" happend.
Luckily I succeeded today in getting a stacktrace of the issue:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-remote-resources-plugin:1.5:process (default) on project parent: Error rendering velocity resource. NullPointerException -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-remote-resources-plugin:1.5:process (default) on project parent: Error rendering velocity resource.
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:212)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
	at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
	at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:307)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193)
	at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106)
	at org.apache.maven.cli.MavenCli.execute(MavenCli.java:863)
	at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288)
	at org.apache.maven.cli.MavenCli.main(MavenCli.java:199)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
	at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
	at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
Caused by: org.apache.maven.plugin.MojoExecutionException: Error rendering velocity resource.
	at org.apache.maven.plugin.resources.remote.ProcessRemoteResourcesMojo.processResourceBundles(ProcessRemoteResourcesMojo.java:1246)
	at org.apache.maven.plugin.resources.remote.ProcessRemoteResourcesMojo.execute(ProcessRemoteResourcesMojo.java:520)
	at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:134)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:207)
	... 20 more
Caused by: java.lang.NullPointerException
	at org.apache.maven.plugin.resources.remote.ProcessRemoteResourcesMojo.processResourceBundles(ProcessRemoteResourcesMojo.java:1232)
	... 23 more
[ERROR] 
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

Looking into the code I noticed that an "unguarded close()" in a finally-block is the culprit. By replacing it with a call to IOUtil.close() the problem is gone. See the attached patch/diff.