[Trinidad] New API addition for Trinidad's UIXCollection

[Jing Wu]

Hi,

This is for JIRA https://issues.apache.org/jira/browse/TRINIDAD-2471.
UIXCollection caches the current row key in its internal state. There 
are cases that the row key becomes stale / invalid in the middle of 
processing a row. A new API invalidateCurrentRowKey() is added to 
UIXCollection to clear out the cached current row key, so next time when 
it is requested, this current new key will be recalculated from model.


  /**
   * Invalidate the cached current row key so it will be recalculated
   * from the model next time when it is requested.
   */
  public void invalidateCurrentRowKey()
  {
  }

Any comment is welcome!

Thanks,
Jing