code: public boolean isInValueSet(Value value) {
          if (value == null) {
              throw new IllegalArgumentException("value cannot be null");
          }
  
          boolean result = true;
          if (!this.valuesKeySet.isEmpty()) {
              result = this.valuesKeySet.contains(value);
          } else if (this.lowerBound != null || this.upperBound != null) {
              if (this.lowerBound != null
                      && !ValueComparator.GREATER_THAN_OR_EQUAL_TO.compare(
                      value, this.lowerBound)) {
                  result = false;
              }
              if (this.upperBound != null
                      && !ValueComparator.LESS_THAN_OR_EQUAL_TO.compare(
                      value, this.upperBound)) {
                  result = false;
              }
          }
          return result;
      }
docs: Returns whether the specified value is in the value set.
  
  @param value a {@link Value}. Cannot be <code>null</code>.
  @return <code>true</code> or <code>false</code>.