Method from

guava/src/com/google/common/reflect/ClassPath.java:123–139

Returns a {@code ClassPath} representing all classes and resources loadable from {@code classloader} and its ancestor class loaders. <p><b>Warning:</b> {@code ClassPath} can find classes and resources only from: <ul> <li>{@link URLClassLoader} instances' {@code file:} URLs <li>the {@linkplain

(ClassLoader classloader)

   *     failed.
   */
  public static ClassPath from(ClassLoader classloader) throws IOException {
    ImmutableSet<LocationInfo> locations = locationsFrom(classloader);

    // Add all locations to the scanned set so that in a classpath [jar1, jar2], where jar1 has a
    // manifest with Class-Path pointing to jar2, we won't scan jar2 twice.
    Set<File> scanned = new HashSet<>();
    for (LocationInfo location : locations) {
      scanned.add(location.file());
    }

    // Scan all locations
    ImmutableSet.Builder<ResourceInfo> builder = ImmutableSet.builder();
    for (LocationInfo location : locations) {
      builder.addAll(location.scanResources(scanned));
    }
    return new ClassPath(builder.build());
  }

  /**
   * Returns all resources loadable from the current class path, including the class files of all