private VTMatchTagDB getMatchTagDB(String tagName) {
		Set<VTMatchTag> matchTags = getMatchTags();
		for (VTMatchTag matchTag : matchTags) {
			// Return the tag if we already have it
			if (matchTag.getName().equals(tagName)) {
				return (VTMatchTagDB) matchTag;
			}
		}
		return null;
	}
Mark the state of a Version Tracking item as having changed and generate
the event of the specified type.  Any or all parameters may be null.
@param eventType event type
@param affected the version tracking object that was affected by the change.
@param oldValue original value or an Object that is related to the event.
@param newValue new value or an Object that is related to the event.
Ghidra/Features/VersionTracking/src/main/java/ghidra/feature/vt/api/db/VTSessionDB.java