public boolean isClosed() {
			return dtm instanceof FileDataTypeManager fdtm
					? fdtm.isClosed()
					: false;
		}
Simple, non-ui implementation of the {@link DataTypeArchiveService} interface.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/datamgr/archive/DefaultDataTypeArchiveService.java