wro4j-core/src/main/java/ro/isdc/wro/util/Transformers.java
public static Transformer<String> baseNameSuffixTransformer(final String suffix) {
    return new Transformer<String>() {
      public String transform(final String input) {
        final String baseName = FilenameUtils.getBaseName(input);
        final String extension = FilenameUtils.getExtension(input);
        return baseName + suffix + "." + extension;
      }
    };
  }
public static Transformer<String> baseNameSuffixTransformer(final String suffix) {
    return new Transformer<String>() {
      public String transform(final String input) {
        final String baseName = FilenameUtils.getBaseName(input);
        final String extension = FilenameUtils.getExtension(input);
        return baseName + suffix + "." + extension;
      }
    };
  }
Appends a suffix to the source baseName.
@param suffix to append.
@return {@link Transformer} capable to append a suffix to provided baseName.