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