API Deprecate FormField API

src/Forms/DateField.php

@@ -101,6 +101,7 @@ class DateField extends TextField
      * to detect invalid values.
      *
      * @var mixed
+     * @deprecated 5.4.0 Use $value instead
      */
     protected $rawValue = null;
 

src/Forms/DatetimeField.php

@@ -75,6 +75,7 @@ class DatetimeField extends TextField
      * to detect invalid values.
      *
      * @var mixed
+     * @deprecated 5.4.0 Use $value instead
      */
     protected $rawValue = null;
 

src/Forms/FormField.php

@@ -15,6 +15,7 @@
 use SilverStripe\View\AttributesHTML;
 use SilverStripe\View\SSViewer;
 use SilverStripe\View\ViewableData;
+use SilverStripe\Dev\Deprecation;
 
 /**
  * Represents a field in a form.
@@ -1223,9 +1224,11 @@ public function Type()
      * @param bool $result
      * @param Validator $validator
      * @return bool
+     * @deprecated 5.4.0 Use extend() directly instead
      */
     protected function extendValidationResult(bool $result, Validator $validator): bool
     {
+        Deprecation::notice('5.4.0', 'Use extend() directly instead');
         $this->extend('updateValidationResult', $result, $validator);
         return $result;
     }

src/Forms/TimeField.php

@@ -48,6 +48,7 @@ class TimeField extends TextField
      * to detect invalid values.
      *
      * @var mixed
+     * @deprecated 5.4.0 Use $value instead
      */
     protected $rawValue = null;