Repeatedly I'm getting a popup error window saying:
Errors occurred during the build.
Errors running builder 'CDI (Context and Dependency Injection) Builder' on project 'shop'.
java.lang.NullPointerException

The according stacktrace of this annoying message:
java.lang.NullPointerException
at org.jboss.tools.common.util.EclipseJavaUtil.findField(EclipseJavaUtil.java:164)
at org.jboss.tools.common.util.EclipseJavaUtil.findField(EclipseJavaUtil.java:161)
at org.jboss.tools.common.java.impl.AnnotationDeclaration.validateNamedValue(AnnotationDeclaration.java:140)
at org.jboss.tools.common.java.impl.AnnotationDeclaration.resolveMemberValue(AnnotationDeclaration.java:119)
at org.jboss.tools.common.java.impl.AnnotationDeclaration.setDeclaration(AnnotationDeclaration.java:50)
at org.jboss.tools.cdi.internal.core.impl.definition.AbstractMemberDefinition.addAnnotation(AbstractMemberDefinition.java:112)
at org.jboss.tools.cdi.internal.core.impl.definition.AbstractMemberDefinition.init(AbstractMemberDefinition.java:104)
at org.jboss.tools.cdi.internal.core.impl.definition.AbstractMemberDefinition.setAnnotatable(AbstractMemberDefinition.java:64)
at org.jboss.tools.cdi.internal.core.impl.definition.PackageDefinition.setPackage(PackageDefinition.java:54)
at org.jboss.tools.cdi.internal.core.scanner.CDIBuilderDelegate.build(CDIBuilderDelegate.java:88)
at org.jboss.tools.cdi.internal.core.scanner.CDIBuilderDelegate.build(CDIBuilderDelegate.java:48)
at org.jboss.tools.cdi.core.CDICoreBuilder.invokeBuilderDelegates(CDICoreBuilder.java:326)
at org.jboss.tools.cdi.core.CDICoreBuilder.fullBuild(CDICoreBuilder.java:261)
at org.jboss.tools.cdi.core.CDICoreBuilder.build(CDICoreBuilder.java:221)
at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:728)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:199)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:239)
at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:292)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:295)
at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:351)
at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:374)
at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:143)
at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:241)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)