fix: ensure invalid state is correctly set on slotted pickers (#7074) (#7077)

Co-authored-by: Serhii Kulykov <iamkulykov@gmail.com>

Author: vaadin-bot

vaadin-date-time-picker-flow-parent/vaadin-date-time-picker-flow/src/main/java/com/vaadin/flow/component/datetimepicker/DateTimePicker.java

@@ -425,6 +425,13 @@ public void setReadOnly(boolean readOnly) {
         timePicker.setReadOnly(readOnly);
     }
 
+    @Override
+    public void setInvalid(boolean invalid) {
+        HasValidationProperties.super.setInvalid(invalid);
+        datePicker.setInvalid(invalid);
+        timePicker.setInvalid(invalid);
+    }
+
     /**
      * Sets the label for this field.
      *

vaadin-date-time-picker-flow-parent/vaadin-date-time-picker-flow/src/test/java/com/vaadin/flow/component/datetimepicker/validation/BasicValidationTest.java

@@ -23,6 +23,7 @@
 import com.vaadin.flow.component.datepicker.DatePicker;
 import com.vaadin.flow.component.datetimepicker.DateTimePicker;
 import com.vaadin.flow.component.shared.SlotUtils;
+import com.vaadin.flow.component.timepicker.TimePicker;
 import com.vaadin.flow.dom.DomEvent;
 import com.vaadin.flow.internal.nodefeature.ElementListenerMap;
 import com.vaadin.tests.validation.AbstractBasicValidationTest;
@@ -124,6 +125,13 @@ public void setI18nAndCustomErrorMessage_validate_removeCustomErrorMessage_valid
         Assert.assertEquals("Field is required", testField.getErrorMessage());
     }
 
+    @Test
+    public void setInvalid_nestedPickersAreInvalid() {
+        testField.setInvalid(true);
+        Assert.assertTrue(getDatePicker().isInvalid());
+        Assert.assertTrue(getTimePicker().isInvalid());
+    }
+
     @Override
     protected DateTimePicker createTestField() {
         return new DateTimePicker();
@@ -133,6 +141,10 @@ private DatePicker getDatePicker() {
         return (DatePicker) SlotUtils.getChildInSlot(testField, "date-picker");
     }
 
+    private TimePicker getTimePicker() {
+        return (TimePicker) SlotUtils.getChildInSlot(testField, "time-picker");
+    }
+
     private void fireValidatedDomEvent() {
         DomEvent validatedDomEvent = new DomEvent(testField.getElement(),
                 "validated", Json.createObject());