code: public final void initLineSource(String lineSource)
      {
          if (lineSource == null) throw new IllegalArgumentException();
          if (this.lineSource != null) throw new IllegalStateException();
          this.lineSource = lineSource;
      }
docs: Initialize the text of the source line containing the error.
  
  @param lineSource the text of the source line responsible for the error.
  It should not be <tt>null</tt>.
  
  @throws IllegalStateException if the method is called more then once.