Documentation should note that a table header row is required

[Douglas Swartz]

A confluence table without a th row does not render a Pivot Table.

Utils.columnPosition looks for a th row to find matching column names for row, column, and cell values.

I accidentally created a table without a defined header row. Of course, Pivot Table rendered nothing.

I suggest the documentation be altered to call out this requirement. Of course, the code could be changed to use the first row if no th is present, but I think that's definitely optional.

A message, similar to the message displayed when no table is present, would immediately help the user understand why no pivot table was rendered.

[Xavier Arques]

I will update the documentation and display an error message in case no header is present

[Xavier Arques]

Fixed in version 1.5.3: Pivot Table works now with table without header. Add unit tests and functional tests