feat(model): add carousel and card Block Kit blocks

slack-api-model/src/main/java/com/slack/api/model/block/Blocks.java

@@ -129,4 +129,14 @@ public static ShareShortcutBlock shareShortcut() {
         return ShareShortcutBlock.builder().build();
     }
 
+    // CardBlock
+    public static CardBlock card(ModelConfigurator<CardBlock.CardBlockBuilder> configurator) {
+        return configurator.configure(CardBlock.builder()).build();
+    }
+
+    // CarouselBlock
+    public static CarouselBlock carousel(ModelConfigurator<CarouselBlock.CarouselBlockBuilder> configurator) {
+        return configurator.configure(CarouselBlock.builder()).build();
+    }
+
 }

slack-api-model/src/main/java/com/slack/api/model/block/CardBlock.java

@@ -0,0 +1,67 @@
+package com.slack.api.model.block;
+
+import com.slack.api.model.block.element.ImageElement;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+/**
+ * A card is a layout block used to display a compact, structured summary of content. It can be used on its own
+ * or grouped together inside a {@link CarouselBlock carousel}. At least one of {@code heroImage}, {@code title},
+ * {@code actions}, or {@code body} must be provided.
+ *
+ * https://docs.slack.dev/reference/block-kit/blocks/card-block
+ */
+@Data
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class CardBlock implements LayoutBlock {
+    public static final String TYPE = "card";
+    private final String type = TYPE;
+
+    /**
+     * Link to the top image used on the card. Max length of 3000 characters.
+     */
+    private ImageElement heroImage;
+
+    /**
+     * Small image displayed beside the title and subtitle. Max length of 3000 characters.
+     * Mutually exclusive with {@code slackIcon}.
+     */
+    private ImageElement icon;
+
+    /**
+     * The name of a built-in Slack icon to display beside the title and subtitle.
+     * Mutually exclusive with {@code icon}.
+     */
+    private String slackIcon;
+
+    /**
+     * The title of the card. 150 character maximum.
+     */
+    private String title;
+
+    /**
+     * The subtitle of the card. 150 character maximum.
+     */
+    private String subtitle;
+
+    /**
+     * The main text of the card. 200 character maximum.
+     */
+    private String body;
+
+    /**
+     * Secondary text displayed beneath the body. 200 character maximum.
+     */
+    private String subtext;
+
+    /**
+     * An {@link ActionsBlock actions block} containing a maximum of 3 buttons.
+     */
+    private ActionsBlock actions;
+
+    private String blockId;
+}

slack-api-model/src/main/java/com/slack/api/model/block/CarouselBlock.java

@@ -0,0 +1,32 @@
+package com.slack.api.model.block;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A carousel is a layout block used to display a horizontally scrollable collection of
+ * {@link CardBlock cards}. It must contain between 1 and 10 cards.
+ *
+ * https://docs.slack.dev/reference/block-kit/blocks/carousel-block
+ */
+@Data
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class CarouselBlock implements LayoutBlock {
+    public static final String TYPE = "carousel";
+    private final String type = TYPE;
+
+    /**
+     * An array of {@link CardBlock card} blocks. Must contain between 1 and 10 cards.
+     */
+    @Builder.Default
+    private List<CardBlock> elements = new ArrayList<>();
+
+    private String blockId;
+}

slack-api-model/src/main/java/com/slack/api/util/json/GsonLayoutBlockFactory.java

@@ -61,6 +61,10 @@ private Class<? extends LayoutBlock> getLayoutClassInstance(String typeName) {
                 return RichTextBlock.class;
             case ShareShortcutBlock.TYPE:
                 return ShareShortcutBlock.class;
+            case CardBlock.TYPE:
+                return CardBlock.class;
+            case CarouselBlock.TYPE:
+                return CarouselBlock.class;
             default:
                 if (failOnUnknownProperties) {
                     throw new JsonParseException("Unsupported layout block type: " + typeName);

slack-api-model/src/test/java/test_locally/api/model/block/BlockKitTest.java

@@ -15,8 +15,10 @@
 import static com.slack.api.model.block.Blocks.*;
 import static com.slack.api.model.block.composition.BlockCompositions.asSectionFields;
 import static com.slack.api.model.block.composition.BlockCompositions.plainText;
+import static com.slack.api.model.block.element.BlockElements.button;
 import static com.slack.api.model.block.element.BlockElements.checkboxes;
 import static com.slack.api.model.block.element.BlockElements.conversationsSelect;
+import static com.slack.api.model.block.element.BlockElements.image;
 import static com.slack.api.model.view.Views.view;
 import static com.slack.api.model.view.Views.viewSubmit;
 import static org.hamcrest.CoreMatchers.*;
@@ -1940,4 +1942,99 @@ public void parseRichTextElements() {
         RichTextSectionElement section = (RichTextSectionElement) ((RichTextBlock) message.getBlocks().get(0)).getElements().get(0);
         assertThat(section.getElements().size(), is(10));
     }
+
+    @Test
+    public void parseCarouselBlock() {
+        // https://docs.slack.dev/reference/block-kit/blocks/carousel-block
+        String json = "{\n" +
+                "  \"blocks\": [\n" +
+                "    {\n" +
+                "      \"type\": \"carousel\",\n" +
+                "      \"block_id\": \"carousel-1\",\n" +
+                "      \"elements\": [\n" +
+                "        {\n" +
+                "          \"type\": \"card\",\n" +
+                "          \"block_id\": \"card-1\",\n" +
+                "          \"title\": \"First card\",\n" +
+                "          \"subtitle\": \"Subtitle one\",\n" +
+                "          \"body\": \"Body of the first card.\",\n" +
+                "          \"hero_image\": {\n" +
+                "            \"type\": \"image\",\n" +
+                "            \"image_url\": \"https://example.com/hero.png\",\n" +
+                "            \"alt_text\": \"hero\"\n" +
+                "          },\n" +
+                "          \"icon\": {\n" +
+                "            \"type\": \"image\",\n" +
+                "            \"image_url\": \"https://example.com/icon.png\",\n" +
+                "            \"alt_text\": \"icon\"\n" +
+                "          },\n" +
+                "          \"actions\": {\n" +
+                "            \"type\": \"actions\",\n" +
+                "            \"elements\": [\n" +
+                "              {\n" +
+                "                \"type\": \"button\",\n" +
+                "                \"action_id\": \"open\",\n" +
+                "                \"text\": {\"type\": \"plain_text\", \"text\": \"Open\"}\n" +
+                "              }\n" +
+                "            ]\n" +
+                "          }\n" +
+                "        },\n" +
+                "        {\n" +
+                "          \"type\": \"card\",\n" +
+                "          \"title\": \"Second card\"\n" +
+                "        }\n" +
+                "      ]\n" +
+                "    }\n" +
+                "  ]\n" +
+                "}";
+        Message message = GsonFactory.createSnakeCase().fromJson(json, Message.class);
+        assertThat(message, is(notNullValue()));
+        assertThat(message.getBlocks().size(), is(1));
+
+        CarouselBlock carousel = (CarouselBlock) message.getBlocks().get(0);
+        assertThat(carousel.getType(), is("carousel"));
+        assertThat(carousel.getBlockId(), is("carousel-1"));
+        assertThat(carousel.getElements().size(), is(2));
+
+        CardBlock firstCard = carousel.getElements().get(0);
+        assertThat(firstCard.getType(), is("card"));
+        assertThat(firstCard.getBlockId(), is("card-1"));
+        assertThat(firstCard.getTitle(), is("First card"));
+        assertThat(firstCard.getSubtitle(), is("Subtitle one"));
+        assertThat(firstCard.getBody(), is("Body of the first card."));
+        assertThat(firstCard.getHeroImage().getImageUrl(), is("https://example.com/hero.png"));
+        assertThat(firstCard.getIcon().getImageUrl(), is("https://example.com/icon.png"));
+        assertThat(firstCard.getActions().getElements().size(), is(1));
+
+        CardBlock secondCard = carousel.getElements().get(1);
+        assertThat(secondCard.getTitle(), is("Second card"));
+        assertThat(secondCard.getBlockId(), is(nullValue()));
+    }
+
+    @Test
+    public void buildCarouselBlock() {
+        CarouselBlock block = carousel(c -> c
+                .blockId("carousel-1")
+                .elements(Arrays.asList(
+                        card(card -> card
+                                .blockId("card-1")
+                                .title("Promo")
+                                .body("Check this out")
+                                .heroImage(image(i -> i.imageUrl("https://example.com/hero.png").altText("hero")))
+                                .actions(actions(Arrays.asList(
+                                        button(b -> b.actionId("open").text(plainText("Open"))))))),
+                        card(card -> card.title("Second")))));
+        assertThat(block.getType(), is("carousel"));
+        assertThat(block.getElements().size(), is(2));
+
+        Gson gson = GsonFactory.createSnakeCase();
+        String output = gson.toJson(block);
+        CarouselBlock parsed = gson.fromJson(output, CarouselBlock.class);
+        assertThat(parsed.getBlockId(), is("carousel-1"));
+        assertThat(parsed.getElements().size(), is(2));
+        assertThat(parsed.getElements().get(0).getType(), is("card"));
+        assertThat(parsed.getElements().get(0).getTitle(), is("Promo"));
+        assertThat(parsed.getElements().get(0).getHeroImage().getImageUrl(), is("https://example.com/hero.png"));
+        assertThat(parsed.getElements().get(0).getActions().getElements().size(), is(1));
+    }
 }