wro4j-core/src/main/java/ro/isdc/wro/model/transformer/WildcardExpanderModelTransformer.java
public Function<Collection<File>, Void> createExpanderHandler(final Group group, final Resource resource,
      final String baseNameFolder) {
    LOG.debug("createExpanderHandler using baseNameFolder: {}\n for resource {}", baseNameFolder, resource);
    return new Function<Collection<File>, Void>() {
      public Void apply(final Collection<File> files) {
        if (baseNameFolder == null) {
          // replacing group with empty list since the original uri has no associated resources.
          // No BaseNameFolder found
          LOG.warn("The resource {} is probably invalid, removing it from the group.", resource);
          group.replace(resource, new ArrayList<Resource>());
        } else {
          final List<Resource> expandedResources = new ArrayList<Resource>();
          LOG.debug("baseNameFolder: {}", baseNameFolder);
          for (final File file : files) {
            final String resourcePath = getFullPathNoEndSeparator(resource);
            LOG.debug("\tresourcePath: {}", resourcePath);
            LOG.debug("\tfile path: {}", file.getPath());
            final String computedResourceUri = resourcePath
                + StringUtils.removeStart(file.getPath(), baseNameFolder).replace('\\', '/');

            final Resource expandedResource = Resource.create(computedResourceUri, resource.getType());
            LOG.debug("\texpanded resource: {}", expandedResource);
            expandedResources.add(expandedResource);
          }
          LOG.debug("\treplace resource {}", resource);
          group.replace(resource, expandedResources);
        }
        return null;
      }

      /**
       * This method fixes the problem when a resource in a group uses deep wildcard and starts at the root.
       * <p/>
       * Find more details <a href="https://github.com/alexo/wro4j/pull/44">here</a>.
       */
      private String getFullPathNoEndSeparator(final Resource resource1) {
        final String result = FilenameUtils.getFullPathNoEndSeparator(resource1.getUri());
        if (result != null && 1 == result.length() && 0 == FilenameUtils.indexOfLastSeparator(result)) {
          return "";
        }

        return result;
      }
    };
  }
public Function<Collection<File>, Void> createExpanderHandler(final Group group, final Resource resource,
      final String baseNameFolder) {
    LOG.debug("createExpanderHandler using baseNameFolder: {}\n for resource {}", baseNameFolder, resource);
    return new Function<Collection<File>, Void>() {
      public Void apply(final Collection<File> files) {
        if (baseNameFolder == null) {
          // replacing group with empty list since the original uri has no associated resources.
          // No BaseNameFolder found
          LOG.warn("The resource {} is probably invalid, removing it from the group.", resource);
          group.replace(resource, new ArrayList<Resource>());
        } else {
          final List<Resource> expandedResources = new ArrayList<Resource>();
          LOG.debug("baseNameFolder: {}", baseNameFolder);
          for (final File file : files) {
            final String resourcePath = getFullPathNoEndSeparator(resource);
            LOG.debug("\tresourcePath: {}", resourcePath);
            LOG.debug("\tfile path: {}", file.getPath());
            final String computedResourceUri = resourcePath
                + StringUtils.removeStart(file.getPath(), baseNameFolder).replace('\\', '/');

            final Resource expandedResource = Resource.create(computedResourceUri, resource.getType());
            LOG.debug("\texpanded resource: {}", expandedResource);
            expandedResources.add(expandedResource);
          }
          LOG.debug("\treplace resource {}", resource);
          group.replace(resource, expandedResources);
        }
        return null;
      }

      /**
       * This method fixes the problem when a resource in a group uses deep wildcard and starts at the root.
       * <p/>
       * Find more details <a href="https://github.com/alexo/wro4j/pull/44">here</a>.
       */
      private String getFullPathNoEndSeparator(final Resource resource1) {
        final String result = FilenameUtils.getFullPathNoEndSeparator(resource1.getUri());
        if (result != null && 1 == result.length() && 0 == FilenameUtils.indexOfLastSeparator(result)) {
          return "";
        }

        return result;
      }
    };
  }
create the handler which expand the resources containing wildcard.