code: public void clearListField(String fieldName) {
  		Object val = getFieldValue(fieldName, true); // internal
  		if (val instanceof List<?>)
  			((List<?>)val).clear();
  		else if (val != null && val.getClass().isArray()) {
  			DOField fld = getDomainObjectType().getFieldByName(fieldName);
  			String ctn = fld.getComponentTypeName();
  			Class<?> clazz;
  			try {
  				clazz = getDomainObjectType().getDomainModel().getClassForName(ctn);
  				tryInitListOrArray(null, fld, clazz);
  			} catch (ClassNotFoundException e) {
  				throw new RuntimeException(e);
  			}
  		} else {
  			if (!getDomainObjectType().getFieldByName(fieldName).isListOrArray())
  				throw new RuntimeException("field: [" + fieldName + "] is neither list nor array");
  			if (val == null)
  				throw new RuntimeException("list or array field: [" + fieldName + "] is null");
  		}
  	}
docs: Removes all of the elements from the list field.
  @param fieldName