docs: public ClassInfoList getSubclasses(final String superclassName) {
          if (closed.get()) {
              throw new IllegalArgumentException("Cannot use a ScanResult after it has been closed");
          }
          if (!scanSpec.enableClassInfo) {
              throw new IllegalArgumentException("Please call ClassGraph#enableClassInfo() before #scan()");
          }
          if (superclassName.equals("java.lang.Object")) {
              // Return all standard classes (interfaces don't extend Object)
              return getAllStandardClasses();
          } else {
              final ClassInfo superclass = classNameToClassInfo.get(superclassName);
              return superclass == null ? ClassInfoList.EMPTY_LIST : superclass.getSubclasses();
          }
      }