code: public ClassInfoList getSubclasses() {
          if (getName().equals("java.lang.Object")) {
              // Make an exception for querying all subclasses of java.lang.Object
              return scanResult.getAllClasses();
          } else {
              return new ClassInfoList(
                      this.filterClassInfo(RelType.SUBCLASSES, /* strictWhitelist = */ !isExternalClass),
                      /* sortByName = */ true);
          }
      }
docs: Get the subclasses of this class, sorted in order of name. Call {@link ClassInfoList#directOnly()} to get
  direct subclasses.
  
  @return the list of subclasses of this class, or the empty list if none.