Created attachment 163512 [details]
Screenshot

Dev build. Open https://github.com/stapler/netbeans-stapler-plugin/blob/2f8b9b6d9bdd777012c582315775e400d31b8742/pom.xml and its modules. You will see error badges on the generated `Bundle.java`, on the node and on the editor tab, and errors under Action Items—even though no errors are shown inline in the editor, the status box is green, and clicking on the usages of `NbBundle` jumps to the corresponding sources as expected.

Opening the Properties of the `Bundle.java` node shows the compile classpath including `org-openide-util-*.jar` as expected, so I do not think the `maven` module is doing anything wrong here. The metadata inspector output looks right:

Java source roots:
  "Source Packages" (1SourceRoot): …/stapler-plugin/src/main/java
    source level: 1.7
    encoding: UTF-8
    binaries: …/stapler-plugin/target/classes ~/.m2/repository/org/kohsuke/stapler/netbeans/plugin/1.6/plugin-1.6.jar
    test roots: …/stapler-plugin/src/test/java
    classpath/source: …/stapler-plugin/src/main/java …/stapler-plugin/target/generated-sources/annotations …/stapler-plugin/src/main/resources
    classpath/compile:
      …
      ~/.m2/repository/org/netbeans/api/org-openide-util/RELEASE80/org-openide-util-RELEASE80.jar
        sources (informational): ~/.m2/repository/org/netbeans/api/org-openide-util/RELEASE80/org-openide-util-RELEASE80-sources.jar
      …
      …/stapler-plugin/target/classes
        sources (authoritative): …/stapler-plugin/src/main/java …/stapler-plugin/target/generated-sources/annotations …/stapler-plugin/src/main/resources
  …

Whatever is amiss, it is clearly incorrect for the Java infrastructure to be reporting compilation errors in some places yet showing no errors in the actual source lines.