public String dataToString(D data){
  StringBuilder sb=new StringBuilder(64);
  DebugUtils.buildShortClassTag(data,sb);
  sb.append("}");
  return sb.toString();
}

public String dataToString ( D data ) { StringBuilder sb = new StringBuilder ( 64 ) ; DebugUtils . buildShortClassTag ( data , sb ) ; sb . append ( "}" ) ; return sb . toString ( ) ; }
for debugging , converts an instance of the loader ' s data class to a string that can be printed . must handle a null data .
