public void add(InputStream is,boolean doSubstitutions) throws IOException {
  Properties props=new Properties();
  props.load(is);
  if (doSubstitutions)   substituteSystemValues(props);
  add(props);
}

public void add ( InputStream is , boolean doSubstitutions ) throws IOException { Properties props = new Properties ( ) ; props . load ( is ) ; if ( doSubstitutions ) substituteSystemValues ( props ) ; add ( props ) ; }
adds values from java properties file format . current values are kept except if it exists in the stream , in which case it is overwritten .
