docs: private void scheduleScanningIfExternalClass(final String className, final String relationship) {
          // Don't scan Object
          if (className != null && !className.equals("java.lang.Object")
          // Only schedule each external class once for scanning, across all threads
                  && classNamesScheduledForScanning.add(className)) {
              // Search for the named class' classfile among classpath elements, in classpath order (this is O(N)
              // for each class, but there shouldn't be too many cases of extending scanning upwards)
              final String classfilePath = JarUtils.classNameToClassfilePath(className);
              // First check current classpath element, to avoid iterating through other classpath elements
              Resource classResource = classpathElement.getResource(classfilePath);
              ClasspathElement foundInClasspathElt = null;
              if (classResource != null) {
                  // Found the classfile in the current classpath element
                  foundInClasspathElt = classpathElement;
              } else {
                  // Didn't find the classfile in the current classpath element -- iterate through other elements
                  for (final ClasspathElement classpathOrderElt : classpathOrder) {
                      if (classpathOrderElt != classpathElement) {
                          classResource = classpathOrderElt.getResource(classfilePath);
                          if (classResource != null) {
                              foundInClasspathElt = classpathOrderElt;
                              break;
                          }
                      }
                  }
              }
              if (classResource != null) {
                  // Found class resource 
                  if (log != null) {
                      log.log("Scheduling external class for scanning: " + relationship + " " + className
                              + (foundInClasspathElt == classpathElement ? ""
                                      : " -- found in classpath element " + foundInClasspathElt));
                  }
                  if (additionalWorkUnits == null) {
                      additionalWorkUnits = new ArrayList<>();
                  }
                  // Schedule class resource for scanning
                  additionalWorkUnits.add(new ClassfileScanWorkUnit(foundInClasspathElt, classResource,
                          /* isExternalClass = */ true));
              } else {
                  if (log != null) {
                      log.log("External " + relationship + " " + className + " was not found in "
                              + "non-blacklisted packages -- cannot extend scanning to this class");
                  }
              }
          }
      }