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

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

@@ -0,0 +1,41 @@
+package com.slack.api.model.block;
+
+import com.slack.api.model.block.composition.TextObject;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+/**
+ * https://docs.slack.dev/reference/block-kit/blocks/alert-block
+ * <p>
+ * Displays an inline alert message. Alert blocks are currently only supported in modals.
+ */
+@Data
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class AlertBlock implements LayoutBlock {
+    public static final String TYPE = "alert";
+    private final String type = TYPE;
+
+    /**
+     * The message content of the alert, as a plain_text or mrkdwn text object.
+     * Maximum length for the text in this field is 200 characters.
+     */
+    private TextObject text;
+
+    /**
+     * The severity level of the alert. One of default, info, warning, error, or success.
+     * Will be default if omitted.
+     */
+    private String level;
+
+    /**
+     * A string acting as a unique identifier for a block. If not specified, one will be generated.
+     * Maximum length for this field is 255 characters.
+     * block_id should be unique for each message and each iteration of a message.
+     * If a message is updated, use a new block_id.
+     */
+    private String blockId;
+}

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

@@ -129,4 +129,22 @@ public static ShareShortcutBlock shareShortcut() {
         return ShareShortcutBlock.builder().build();
     }
 
+    // AlertBlock
+
+    public static AlertBlock alert(ModelConfigurator<AlertBlock.AlertBlockBuilder> configurator) {
+        return configurator.configure(AlertBlock.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 +1,75 @@
+package com.slack.api.model.block;
+
+import com.slack.api.model.block.composition.SlackIconObject;
+import com.slack.api.model.block.composition.TextObject;
+import com.slack.api.model.block.element.BlockElement;
+import com.slack.api.model.block.element.ImageElement;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+import java.util.List;
+
+/**
+ * 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;
+
+    /**
+     * A top banner image for the card in the form of an image element.
+     * The image URL may be up to 3000 characters and the alt text up to 2000 characters.
+     */
+    private ImageElement heroImage;
+
+    /**
+     * A small icon displayed next to the title and subtitle in the form of an image element.
+     * The image URL may be up to 3000 characters and the alt text up to 2000 characters.
+     * Mutually exclusive with {@code slackIcon}.
+     */
+    private ImageElement icon;
+
+    /**
+     * A built-in Slack icon displayed next to the title and subtitle.
+     * Mutually exclusive with {@code icon}.
+     */
+    private SlackIconObject slackIcon;
+
+    /**
+     * The title of the card. Maximum length for the text in this field is 150 characters.
+     */
+    private TextObject title;
+
+    /**
+     * The subtitle of the card. Maximum length for the text in this field is 150 characters.
+     */
+    private TextObject subtitle;
+
+    /**
+     * The body text of the card. Maximum length for the text in this field is 200 characters.
+     */
+    private TextObject body;
+
+    /**
+     * Secondary text displayed beneath the body of the card. Maximum length for the text in this field
+     * is 200 characters.
+     */
+    private TextObject subtext;
+
+    /**
+     * Interactive elements (such as buttons) displayed at the bottom of the card. Up to 3 buttons.
+     */
+    private List<BlockElement> actions;
+
+    private String blockId;
+}

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

@@ -0,0 +1,30 @@
+package com.slack.api.model.block;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+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.
+     */
+    private List<CardBlock> elements;
+
+    private String blockId;
+}

slack-api-model/src/main/java/com/slack/api/model/block/composition/BlockCompositions.java

@@ -87,4 +87,14 @@ public static FeedbackButtonObject feedbackButton(ModelConfigurator<FeedbackButt
     public static SlackFileObject slackFile(ModelConfigurator<SlackFileObject.SlackFileObjectBuilder> configurator) {
         return configurator.configure(SlackFileObject.builder()).build();
     }
+
+    // SlackIconObject
+
+    public static SlackIconObject slackIcon(ModelConfigurator<SlackIconObject.SlackIconObjectBuilder> configurator) {
+        return configurator.configure(SlackIconObject.builder()).build();
+    }
+
+    public static SlackIconObject slackIcon(String name) {
+        return SlackIconObject.builder().name(name).build();
+    }
 }

slack-api-model/src/main/java/com/slack/api/model/block/composition/SlackIconObject.java

@@ -0,0 +1,25 @@
+package com.slack.api.model.block.composition;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+/**
+ * Defines a built-in Slack icon that can be displayed next to the title and subtitle of a card block.
+ *
+ * @see <a href="https://docs.slack.dev/reference/block-kit/composition-objects/slack-icon-object">document</a>
+ */
+@Data
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class SlackIconObject {
+    public static final String TYPE = "icon";
+    private final String type = TYPE;
+
+    /**
+     * The name of the built-in Slack icon.
+     */
+    private String name;
+}

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

@@ -61,6 +61,12 @@ private Class<? extends LayoutBlock> getLayoutClassInstance(String typeName) {
                 return RichTextBlock.class;
             case ShareShortcutBlock.TYPE:
                 return ShareShortcutBlock.class;
+            case AlertBlock.TYPE:
+                return AlertBlock.class;
+            case CardBlock.TYPE:
+                return CardBlock.class;
+            case CarouselBlock.TYPE:
+                return CarouselBlock.class;
             default:
                 if (failOnUnknownProperties) {
                     throw new JsonParseException("Unsupported layout block type: " + typeName);