code: public ClassInfoList getClassesWithAnnotation(final String annotationName) {
          if (closed.get()) {
              throw new IllegalArgumentException("Cannot use a ScanResult after it has been closed");
          }
          if (!scanSpec.enableClassInfo || !scanSpec.enableAnnotationInfo) {
              throw new IllegalArgumentException(
                      "Please call ClassGraph#enableClassInfo() and #enableAnnotationInfo() before #scan()");
          }
          final ClassInfo classInfo = classNameToClassInfo.get(annotationName);
          return classInfo == null ? ClassInfoList.EMPTY_LIST : classInfo.getClassesWithAnnotation();
      }
docs: Get classes with the named class annotation or meta-annotation.
  
  @param annotationName
  The name of the class annotation or meta-annotation.
  @return A list of all non-annotation classes that were found with the named class annotation during the scan,
  or the empty list if none.