code: protected void performFiltering(CharSequence text, int start, int end, int keyCode) {
          if(mAutoCompleteMode == AUTOCOMPLETE_MODE_MULTI)
              ((InternalMultiAutoCompleteTextView)mInputView).superPerformFiltering(text, start, end, keyCode);
      }
docs: <p>Starts filtering the content of the drop down list. The filtering
  pattern is the specified range of text from the edit box. Subclasses may
  override this method to filter with a different pattern, for
  instance a smaller substring of <code>text</code>.</p>