void moveSelectedParameterDown() {
		if (!canMoveParameterDown()) {
			throw new AssertException("Attempted to move parameters down when not allowed.");
		}

		listener.tableRowsChanged();

		ParamInfo p = getSelectedParam();
		functionData.moveParameterDown(p.getOrdinal());
		notifyDataChanged();
	}
Get the effective function to which changes will be made.  This
will be the same as function unless it is a thunk in which case
the returned function will be the ultimate non-thunk function.
@return non-thunk function
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/function/editor/FunctionEditorModel.java