docs: private void addOperator(final String operator) {
          // This should never happen but sanity check...
          Validate.notNull(operator);
  
          if(lastOperator == null) {
              lastOperator = operator;
          }
  
          /* Logic to determine whether to put parentheses around the existing fieldtext. This is tied to the use of the
           * NOT operator as it also adds parentheses.
           */
          if(not) {
              if(componentCount == 1) {
                  fieldTextString.insert(0, "NOT+");
              } else {
                  fieldTextString.insert(0, "NOT(").append(')');
              }
          } else if(!lastOperator.equals(operator)) {
              fieldTextString.insert(0, '(').append(')');
          }
  
          lastOperator = operator;
  
          fieldTextString.append('+').append(operator).append('+');
      }