code: protected String getRowHeaderValueAsString(final FacesContext context) {
          final ValueExpression veRowHeader = getRowHeaderValueExpression();
          final Object value = veRowHeader.getValue(context.getELContext());
          if (value == null) {
              return Constants.EMPTY_STRING;
          }
          else {
              return value.toString();
          }
      }
docs: Gets the row header text value as a string for use in javascript
  
  @param context
  @return