code: public void setMethod(WeightingMethod method, String fieldName) {
  		WeightingMethod existingmethod = this.customWeights.get(fieldName);
  		if (existingmethod == null) {
  			this.customWeights.put(fieldName, method);
  			return;
  		}
  		// already one specified : check that it is the same as the one we have
  		if (!method.equals(existingmethod))
  			throw new RuntimeException("Already set weight of field "
  					+ fieldName + " to " + existingmethod.toString());
  	}
docs: Sets the weighting scheme for a specific field *