Accessing a field updates another in beforeSave - Strange behavior

Need Help
1

I have an entity with timestamp behavior.
Originaly, I found that data in database was never good for the created field.

I thought of some date formating issues, or the timestamp behavior having something broken.

However I was able to narrow down the possibilities to the beforeSave method, where I have some business code that split an array containing 2 dates into 2 fields for DB insertion.

In fact, when accessing this date field, the created date would somehow update to the same value of that field… WTF ?

Does someone have an idea of what is going on ? This looks to me like a CakePHP related bug ?

This is my beforeSave (results speak more than my sentences) :

public function beforeSave(Event $event, EntityInterface $entity, ArrayObject $options)
{
    var_dump($entity);
    /* Partly reproduced :
      public 'created' => 
        object(Cake\I18n\Time)[612]
          public 'time' => string '2016-10-13T10:05:01+00:00' (length=25)
          public 'timezone' => string 'UTC' (length=3)
          public 'fixedNowTime' => boolean false
      public 'modified' => 
        object(Cake\I18n\Time)[617]
          public 'time' => string '2016-10-13T10:05:01+00:00' (length=25)
          public 'timezone' => string 'UTC' (length=3)
          public 'fixedNowTime' => boolean false
    */

    var_dump($entity->decision_date);
    /* Results in :
        array (size=4)
          'min' => 
            object(Cake\I18n\Time)[612]
              public 'time' => string '2017-07-13T10:05:01+00:00' (length=25)
              public 'timezone' => string 'UTC' (length=3)
              public 'fixedNowTime' => boolean false
          'max' => 
            object(Cake\I18n\Time)[612]
              public 'time' => string '2017-07-13T10:05:01+00:00' (length=25)
              public 'timezone' => string 'UTC' (length=3)
              public 'fixedNowTime' => boolean false
          'sameYear' => boolean true
          'past' => boolean false
    */

    var_dump($entity);
    /* Partly reproduced :
      public 'created' => 
        object(Cake\I18n\Time)[612]
          public 'time' => string '2017-07-13T10:05:01+00:00' (length=25)
          public 'timezone' => string 'UTC' (length=3)
          public 'fixedNowTime' => boolean false
      public 'modified' => 
        object(Cake\I18n\Time)[617]
          public 'time' => string '2016-10-13T10:01:53+00:00' (length=25)
          public 'timezone' => string 'UTC' (length=3)
          public 'fixedNowTime' => boolean false 
    */

/* The rest of business code was here... But problem persist with only var_dump in the method... */ 

}

Originally posted on StackOverflow here : http://stackoverflow.com/questions/39998361/cakephp-3-wrong-date-inserted-in-db-timestamp-behavior

EDIT - Issue Resolved :

I am working on someone else’s code, and the method _getDecisionDate() had been overridden by the original developer.
In fact, he was using directly created field to set DecisionDate to the right value in the Entity file…

$dateMax = $this->created->modify('+ 2 years');

So problem slved in the end, this wasn’t a big deal but this gave me headache for 1 day