code: public CSSValueImpl parsePropertyValue(final String propertyValue) throws IOException {
          try (InputSource source = new InputSource(new StringReader(propertyValue))) {
              final CSSOMHandler handler = new CSSOMHandler();
              parser_.setDocumentHandler(handler);
              final LexicalUnit lu = parser_.parsePropertyValue(source);
              if (null == lu) {
                  return null;
              }
              return new CSSValueImpl(lu);
          }
      }
docs: Parses a input string into a CSSValue.
  
  @param propertyValue the input string
  @return the css value
  @throws IOException if the underlying SAC parser throws an IOException