@Override
  public VirtualFile[] occursInPackagePrefixes(PsiPackage psiPackage) {
    List<VirtualFile> result = new ArrayList<VirtualFile>();
    final Module[] modules = ModuleManager.getInstance(psiPackage.getProject()).getModules();

    for (final Module module : modules) {
      for (final ContentEntry contentEntry :
          ModuleRootManager.getInstance(module).getContentEntries()) {
        final List<SourceFolder> sourceFolders =
            contentEntry.getSourceFolders(JavaModuleSourceRootTypes.SOURCES);
        for (final SourceFolder sourceFolder : sourceFolders) {
          final String packagePrefix = sourceFolder.getPackagePrefix();
          if (packagePrefix.startsWith(psiPackage.getQualifiedName())) {
            final VirtualFile file = sourceFolder.getFile();
            if (file != null) {
              result.add(file);
            }
          }
        }
      }
    }

    return VfsUtil.toVirtualFileArray(result);
  }