change false to null

lib/Gedmo/Timestampable/Mapping/Driver/Annotation.php

@@ -70,7 +70,7 @@ class Annotation extends AbstractAnnotationDriver
                     $field = array(
                         'field' => $field,
                         'trackedField' => $timestampable->field,
-                        'value' => $timestampable->value !== null ? $timestampable->value : false,
+                        'value' => $timestampable->value,
                     );
                 }
                 // properties are unique and mapper checks that, no risk here

lib/Gedmo/Timestampable/Mapping/Driver/Xml.php

@@ -73,7 +73,7 @@ class Xml extends BaseXml
                         $field = array(
                             'field' => $field,
                             'trackedField' => $this->_getAttribute($data, 'field'),
-                            'value' => $this->_isAttributeSet($data, 'value') ? $this->_getAttribute($data, 'value') : false,
+                            'value' => $this->_isAttributeSet($data, 'value') ? $this->_getAttribute($data, 'value') : null,
                         );
                     }
                     $config[$this->_getAttribute($data, 'on')][] = $field;

lib/Gedmo/Timestampable/Mapping/Driver/Yaml.php

@@ -65,7 +65,7 @@ class Yaml extends File implements Driver
                         $field = array(
                             'field' => $field,
                             'trackedField' => $mappingProperty['field'],
-                            'value' => isset($mappingProperty['value']) ? $mappingProperty['value'] : false,
+                            'value' => isset($mappingProperty['value']) ? $mappingProperty['value'] : null,
                         );
                     }
                     $config[$mappingProperty['on']][] = $field;

lib/Gedmo/Timestampable/TimestampableListener.php

@@ -105,7 +105,7 @@ class TimestampableListener extends MappedEventSubscriber
                                 $value = $changes[1];
                             }
 
-                            if ($options['value'] == $value || $options['value'] === false) {
+                            if ($options['value'] == $value || $options['value'] === null) {
                                 $needChanges = true;
                                 $this->updateField($object, $ea, $meta, $options['field']);
                             }