code: public void decodeField(GettableData gettableData, ENTITY entity) {
          final VALUEFROM valuefrom = decodeFromGettable(gettableData);
          fieldInfo.setter.set(entity, valuefrom);
      }
docs: <ol>
  <li>First extract the column value from the given GettableData (Row, UDTValue, ...)</li>
  <li>Then call the setter on the given entity to set the value</li>
  </ol>
  @param gettableData
  @param entity