code: private void loadJar(final JarFileInfo jarFileInfo) {
          final String JAR_SUFFIX = ".jar";
  
          jarFiles.add(jarFileInfo);
          jarFileInfo.getJarFile()
                  .stream()
                  .parallel()
                  .filter(je -> !je.isDirectory() && je.getName().toLowerCase().endsWith(JAR_SUFFIX))
                  .forEach(je -> {
                      try {
                          JarEntryInfo jarEntryInfo = new JarEntryInfo(jarFileInfo, je);
                          File tempFile = createJarFile(jarEntryInfo);
  
                          debug(String.format("Loading inner JAR %s from temp file %s", jarEntryInfo.getJarEntry(), getFilenameForLog(tempFile)));
  
                          // Construct ProtectionDomain for this inner JAR:
                          URL url = tempFile.toURI().toURL();
                          ProtectionDomain pdParent = jarFileInfo.getProtectionDomain();
                          // 'csParent' is never null: top JAR has it, classloader creates it for child JAR:
                          CodeSource csParent = pdParent.getCodeSource();
                          Certificate[] certParent = csParent.getCertificates();
                          CodeSource csChild = certParent == null
                                  ? new CodeSource(url, csParent.getCodeSigners())
                                  : new CodeSource(url, certParent);
                          ProtectionDomain pdChild = new ProtectionDomain(csChild, pdParent.getPermissions(), pdParent.getClassLoader(), pdParent.getPrincipals());
                          loadJar(new JarFileInfo(new JarFile(tempFile), jarEntryInfo.getName(), jarFileInfo, pdChild, tempFile));
                      } catch (IOException e) {
                          throw new RuntimeException(String.format("Cannot load jar entries from jar %s", je.getName().toLowerCase()), e);
                      } catch (EeClassLoaderException e) {
                          throw new RuntimeException("ERROR on loading inner JAR: " + e.getMessageAll());
                      }
                  });
      }
docs: Loads specified JAR.