synchronized public void addToFilter(ProgramDiffFilter filter) {
		filterFlags |= filter.filterFlags;
	}
set this filter to look for types of differences in addition to those
types where it is already looking for differences.
The filter that is passed as a parameter indicates the additional types
of differences.

@param filter filter indicating the additional types of differences
to look for between the programs.
Ghidra/Features/Base/src/main/java/ghidra/program/util/ProgramDiffFilter.java