There is an issue in ICE-9471 that involves using the properties from a header column for the body column when a property has not itself been specified on the body column. That is, the body column property would take precedence if it were specified, and would otherwise comes from the corresponding header column. To accomplish this, there needs to be a mechanism to determine if a property has been set on a column component. Some of the properties have default values, so simply checking for null won't work.

In the past we've explored ways of implementing attributesThatAreSet, but with ACE we have not, since passthrough attributes are not widely used, and that was the main use case for it. There were difficulties in having a complete list of set properties, including those specified by JSF component superclasses. This is much simpler, since we only need to know about properties that are generated by the ACE generator itself.