code: public StyleSheet append(Object source, NetworkProcessor network, String encoding, SourceType type,
                               Element inline, boolean inlinePriority, StyleSheet sheet, URL base) throws IOException, CSSException {
  
          Preparator preparator = new SimplePreparator(inline, inlinePriority);
          return parseAndImport(source, network, encoding, type, sheet, preparator, base, null);
      }
docs: Appends parsed source to passed style sheet. This style sheet must be
  IMPERATIVELY parsed by this factory to guarantee proper appending
  
  @param source         Source, interpretation depends on {@code type}
  @param type           Type of source provided
  @param inline         Inline element
  @param inlinePriority True when the rule should have an 'inline' (greater) priority
  @param sheet          StyleSheet to be modified
  @return Modified StyleSheet
  @throws IOException  When problem with input stream occurs
  @throws CSSException When unrecoverable exception during parsing occurs