private DataTypeManagerService getDataTypeService(ServiceProvider serviceProvider) {
		DataTypeManagerService service = serviceProvider.getService(DataTypeManagerService.class);
		if (service == null) {
			throw new AssertException("Unable to find required DataTypeManagerService.");
		}
		return service;
	}
Creates a new instance.

@param preferredDtm the preferred {@link DataTypeManager}.  Data types that are found in 
multiple data type managers will be pruned to just the ones already in the preferred data 
type manager.
@param dataTypeService {@link DataTypeManagerService}
Ghidra/Features/Base/src/main/java/ghidra/app/util/datatype/DataTypeDropDownSelectionDataModel.java