On our fastest build agent (i7 QuadCore + hyperthreading) I have a reproducible NPE when running gradlew in --parallel mode. In the complete build log I see two NPE errors at the same time, so I think there is a synchronization issue.
Caused by: java.lang.NullPointerException
at org.apache.maven.project.interpolation.StringSearchModelInterpolator$InterpolateObjectAction.isQualifiedForInterpolation(StringSearchModelInterpolator.java:344)
at org.apache.maven.project.interpolation.StringSearchModelInterpolator$InterpolateObjectAction.traverseObjectWithParents(StringSearchModelInterpolator.java:172)
at org.apache.maven.project.interpolation.StringSearchModelInterpolator$InterpolateObjectAction.traverseObjectWithParents(StringSearchModelInterpolator.java:328)
at org.apache.maven.project.interpolation.StringSearchModelInterpolator$InterpolateObjectAction.run(StringSearchModelInterpolator.java:135)
at org.apache.maven.project.interpolation.StringSearchModelInterpolator$InterpolateObjectAction.run(StringSearchModelInterpolator.java:102)
at org.apache.maven.project.interpolation.StringSearchModelInterpolator.interpolateObject(StringSearchModelInterpolator.java:80)
at org.apache.maven.project.interpolation.StringSearchModelInterpolator.interpolate(StringSearchModelInterpolator.java:62)
at org.apache.maven.project.DefaultMavenProjectBuilder.processProjectLogic(DefaultMavenProjectBuilder.java:990)
at org.apache.maven.project.DefaultMavenProjectBuilder.buildInternal(DefaultMavenProjectBuilder.java:880)
at org.apache.maven.project.DefaultMavenProjectBuilder.buildFromSourceFileInternal(DefaultMavenProjectBuilder.java:508)
at org.apache.maven.project.DefaultMavenProjectBuilder.build(DefaultMavenProjectBuilder.java:200)
at org.apache.maven.artifact.ant.Pom.initialiseMavenProject(Pom.java:211)
at org.apache.maven.artifact.ant.AbstractArtifactTask.initializePom(AbstractArtifactTask.java:527)
at org.apache.maven.artifact.ant.InstallDeployTaskSupport.initializePom(InstallDeployTaskSupport.java:59)
at org.apache.maven.artifact.ant.DeployTask.doExecute(DeployTask.java:98)
at org.gradle.api.publication.maven.internal.ant.CustomDeployTask.doExecute(CustomDeployTask.java:39)
at org.apache.maven.artifact.ant.AbstractArtifactTask.execute(AbstractArtifactTask.java:751)
at org.gradle.api.publication.maven.internal.ant.AbstractMavenResolver.execute(AbstractMavenResolver.java:212)
at org.gradle.api.publication.maven.internal.ant.AbstractMavenResolver.publish(AbstractMavenResolver.java:203)
at org.gradle.api.publication.maven.internal.ant.AbstractMavenResolver.publish(AbstractMavenResolver.java:181)
at org.gradle.api.internal.artifacts.ivyservice.DefaultIvyDependencyPublisher.publish(DefaultIvyDependencyPublisher.java:42)
at org.gradle.api.internal.artifacts.ivyservice.IvyBackedArtifactPublisher$1.execute(IvyBackedArtifactPublisher.java:80)
at org.gradle.api.internal.artifacts.ivyservice.IvyBackedArtifactPublisher$1.execute(IvyBackedArtifactPublisher.java:54)
at org.gradle.internal.Transformers$3.transform(Transformers.java:131)
at org.gradle.api.internal.artifacts.ivyservice.DefaultIvyContextManager.withIvy(DefaultIvyContextManager.java:61)
at org.gradle.api.internal.artifacts.ivyservice.DefaultIvyContextManager.withIvy(DefaultIvyContextManager.java:39)
at org.gradle.api.internal.artifacts.ivyservice.IvyBackedArtifactPublisher.publish(IvyBackedArtifactPublisher.java:54)
at org.gradle.api.tasks.Upload.upload(Upload.java:67)