code: public static int getOperatorCode(String operatorName) {
          switch (operatorName) {
              case "lt":
                  return OPERATOR_LT;
              case "le":
                  return OPERATOR_LE;
              case "eq":
                  return OPERATOR_EQ;
              case "ne":
                  return OPERATOR_NE;
              case "ge":
                  return OPERATOR_GE;
              case "gt":
                  return OPERATOR_GT;
              default:
                  throw new IllegalStateException(String.format(ERROR_INVALID_NAME, operatorName));
          }
      }
docs: Gets the {@link NumericRefinement#OPERATOR_GT operator} matching the given short name.
  
  @param operatorName the short name of an operator.
  @return the integer representation of this operator.
  @throws IllegalStateException if operatorName is not a known operator name.