@NotNull
 @Override
 public Collection<JetFile> findFilesForPackage(
     @NotNull FqName fqName, @NotNull GlobalSearchScope searchScope) {
   return PackageIndexUtil.findFilesWithExactPackage(
       fqName, kotlinSourceAndClassFiles(searchScope, project), project);
 }
 @NotNull
 @Override
 public Collection<FqName> getSubPackages(@NotNull FqName fqn, @NotNull GlobalSearchScope scope) {
   return PackageIndexUtil.getSubPackageFqNames(
       fqn, kotlinSourceAndClassFiles(scope, project), project, JetScope.ALL_NAME_FILTER);
 }
 @Override
 public boolean packageExists(@NotNull FqName fqName, @NotNull GlobalSearchScope scope) {
   return PackageIndexUtil.packageExists(
       fqName, kotlinSourceAndClassFiles(scope, project), project);
 }