private DockingActionIf createHorizontalRule(DataTypeManager lastDtm, DataTypeManager nextDtm) {

		String topName = lastDtm.getName();
		String bottomName = nextDtm.getName();
		return new HorizontalRuleAction(getName(), topName, bottomName);
	}
An action to navigate backwards or forwards in the history of data types
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/datamgr/NextPreviousDataTypeAction.java