feat: add disabled dates API to date and date-time pickers

Add server-side disabled-dates support: setDisabledDates for a fixed
list, setDisabledWeekdays, and a DisabledDatesProvider callback that is
called per date. The connector composes these into the web component's
disabledDatesProvider (static rules client-side, the provider via a
@ClientCallable range request evaluated per date on the server) and the
validator rejects disabled values. DateTimePicker delegates the same API
to its date part.

Part of #2867

Author: Artur-

vaadin-date-picker-flow-parent/vaadin-date-picker-flow-integration-tests/src/main/java/com/vaadin/flow/component/datepicker/DatePickerDisabledDatesPage.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2000-2026 Vaadin Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.flow.component.datepicker;
+
+import java.time.LocalDate;
+import java.util.List;
+
+import com.vaadin.flow.component.datepicker.DatePicker.DatePickerI18n;
+import com.vaadin.flow.component.html.Div;
+import com.vaadin.flow.component.html.Paragraph;
+import com.vaadin.flow.router.Route;
+
+/**
+ * Test page for a date picker that combines the two disabled-dates APIs: a
+ * fixed list of disabled dates and a per-date provider. January 2023 is shown,
+ * with January 10th and 20th disabled through the fixed list, and the 15th of
+ * every month disabled through the provider.
+ */
+@Route("vaadin-date-picker/date-picker-disabled-dates")
+public class DatePickerDisabledDatesPage extends Div {
+
+    public static final int PROVIDER_DISABLED_DAY = 15;
+    public static final List<LocalDate> FIXED_DISABLED_DATES = List
+            .of(LocalDate.of(2023, 1, 10), LocalDate.of(2023, 1, 20));
+
+    public DatePickerDisabledDatesPage() {
+        DatePicker datePicker = new DatePicker();
+        datePicker.setId("date-picker");
+        datePicker.setI18n(new DatePickerI18n()
+                .setDateDisabledErrorMessage("Date is not available"));
+        // Show January 2023 when the overlay opens.
+        datePicker.setValue(LocalDate.of(2023, 1, 5));
+
+        // Fixed list of already-booked dates.
+        datePicker.setDisabledDates(FIXED_DISABLED_DATES);
+        // Provider: the 15th of every month.
+        datePicker.setDisabledDatesProvider(date -> {
+            System.out.println("Checking " + date);
+            return date.getDayOfMonth() == PROVIDER_DISABLED_DAY;
+        });
+
+        add(new Paragraph(
+                "Disabled: January 10 and 20, 2023 (fixed list); the 15th of every month (provider)."),
+                datePicker);
+    }
+}

vaadin-date-picker-flow-parent/vaadin-date-picker-flow-integration-tests/src/test/java/com/vaadin/flow/component/datepicker/DatePickerDisabledDatesIT.java

@@ -0,0 +1,92 @@
+/*
+ * Copyright 2000-2026 Vaadin Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.flow.component.datepicker;
+
+import java.time.LocalDate;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.vaadin.flow.component.datepicker.testbench.DatePickerElement;
+import com.vaadin.flow.component.datepicker.testbench.DatePickerElement.MonthCalendarElement;
+import com.vaadin.flow.testutil.TestPath;
+import com.vaadin.tests.AbstractComponentIT;
+
+@TestPath("vaadin-date-picker/date-picker-disabled-dates")
+public class DatePickerDisabledDatesIT extends AbstractComponentIT {
+
+    private DatePickerElement datePicker;
+
+    @Before
+    public void init() {
+        open();
+        datePicker = $(DatePickerElement.class).id("date-picker");
+    }
+
+    @Test
+    public void openOverlay_fixedAndProviderDatesAreDisabled() {
+        datePicker.open();
+
+        MonthCalendarElement january = getJanuary2023();
+        // The provider resolves asynchronously; wait for the 15th to become
+        // disabled once the result arrives.
+        waitUntil(driver -> january.isDateDisabled(
+                DatePickerDisabledDatesPage.PROVIDER_DISABLED_DAY));
+
+        // Fixed disabled dates (January 10 and 20).
+        Assert.assertTrue("January 10 (fixed) should be disabled",
+                january.isDateDisabled(10));
+        Assert.assertTrue("January 20 (fixed) should be disabled",
+                january.isDateDisabled(20));
+        Assert.assertFalse("An unaffected date should remain enabled",
+                january.isDateDisabled(
+                        DatePickerDisabledDatesPage.PROVIDER_DISABLED_DAY + 1));
+    }
+
+    @Test
+    public void selectProviderDisabledDate_fieldIsInvalid() {
+        datePicker.setDate(LocalDate.of(2023, 1,
+                DatePickerDisabledDatesPage.PROVIDER_DISABLED_DAY));
+        Assert.assertTrue("A provider-disabled date should be invalid",
+                datePicker.getPropertyBoolean("invalid"));
+
+        datePicker.setDate(LocalDate.of(2023, 1,
+                DatePickerDisabledDatesPage.PROVIDER_DISABLED_DAY + 1));
+        Assert.assertFalse("An enabled date should be valid",
+                datePicker.getPropertyBoolean("invalid"));
+    }
+
+    @Test
+    public void selectFixedDisabledDate_fieldIsInvalid() {
+        datePicker.setDate(LocalDate.of(2023, 1, 10));
+        Assert.assertTrue("A fixed disabled date should be invalid",
+                datePicker.getPropertyBoolean("invalid"));
+
+        datePicker.setDate(LocalDate.of(2023, 1, 11));
+        Assert.assertFalse("An enabled date should be valid",
+                datePicker.getPropertyBoolean("invalid"));
+    }
+
+    private MonthCalendarElement getJanuary2023() {
+        return datePicker.getOverlayContent().getVisibleMonthCalendars()
+                .stream()
+                .filter(calendar -> "January 2023"
+                        .equals(calendar.getHeaderText()))
+                .findFirst().orElseThrow(() -> new AssertionError(
+                        "January 2023 month calendar not found"));
+    }
+}