code: public static boolean isValid(final String cssValue) {
          // TODO modify to make a strict validation
          if (cssValue == null || StringUtil.isBlank(cssValue)) {
              return false;
          }
  
          final String[] cssValueParts = StringUtil.splitBySpace(cssValue);
  
          ListStyleType listStyleType = null;
          ListStylePosition listStylePosition = null;
          ListStyleImage listStyleImage = null;
  
          for (final String eachPart : cssValueParts) {
              boolean invalid = true;
              if (listStyleType == null && ListStyleType.isValid(eachPart)) {
                  listStyleType = ListStyleType.getThis(eachPart);
                  invalid = false;
              } else if (listStylePosition == null
                      && ListStylePosition.isValid(eachPart)) {
                  listStylePosition = ListStylePosition.getThis(eachPart);
                  invalid = false;
              } else if (listStyleImage == null
                      && ListStyleImage.isValid(eachPart)) {
                  listStyleImage = new ListStyleImage(eachPart);
                  invalid = false;
              }
              if (invalid) {
                  return false;
              }
          }
  
          return listStyleType != null || listStylePosition != null
                  || listStyleImage != null;
      }
docs: checks the given css value is valid for this class. It does't do a strict
  validation.
  
  @param cssValue
  @return
  @since 1.0.0
  @author WFF