Fix null values in message params.

slack-base/src/main/java/com/hubspot/slack/client/methods/params/chat/AbstractChatMessageParams.java

@@ -10,6 +10,7 @@
 import org.immutables.value.Value.Check;
 
 @JsonNaming(SnakeCaseStrategy.class)
+@JsonInclude(JsonInclude.Include.NON_ABSENT)
 public abstract class AbstractChatMessageParams implements MessageParams {
 
   @JsonProperty("channel")

slack-base/src/test/java/com/hubspot/slack/client/methods/params/chat/ChatPostMessageParamsSerializationTest.java

@@ -0,0 +1,111 @@
+package com.hubspot.slack.client.methods.params.chat;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.hubspot.slack.client.jackson.ObjectMapperUtils;
+import java.io.IOException;
+import org.junit.Test;
+
+public class ChatPostMessageParamsSerializationTest {
+
+  private static final String CHANNEL_ID = "C1234567890";
+  private static final String THREAD_TS = "1791374668.950609";
+  private static final String USERNAME = "hubspot (breeze) qa";
+
+  @Test
+  public void itOmitsUnsetOptionalFields() throws IOException {
+    ChatPostMessageParams params = ChatPostMessageParams
+      .builder()
+      .setChannelId(CHANNEL_ID)
+      .setText("post message test")
+      .setThreadTs(THREAD_TS)
+      .build();
+
+    JsonNode json = serialize(params);
+
+    assertThat(json.has("username")).isFalse();
+    assertThat(json.has("icon_emoji")).isFalse();
+    assertThat(json.has("icon_url")).isFalse();
+    assertThat(json.has("link_names")).isFalse();
+    assertThat(json.has("unfurl_links")).isFalse();
+    assertThat(json.has("unfurl_media")).isFalse();
+    assertThat(json.has("reply_broadcast")).isFalse();
+    assertThat(json.has("as_user")).isFalse();
+  }
+
+  @Test
+  public void itDoesNotSerializeAnyNullValues() throws IOException {
+    ChatPostMessageParams params = ChatPostMessageParams
+      .builder()
+      .setChannelId(CHANNEL_ID)
+      .setText("post message test")
+      .build();
+
+    assertThat(serialize(params).toString()).doesNotContain(":null");
+  }
+
+  @Test
+  public void itSerializesSetOptionalFields() throws IOException {
+    ChatPostMessageParams params = ChatPostMessageParams
+      .builder()
+      .setChannelId(CHANNEL_ID)
+      .setText("post message test")
+      .setThreadTs(THREAD_TS)
+      .setUsername(USERNAME)
+      .setIconEmoji(":robot_face:")
+      .setIconUrl("https://example.com/icon.png")
+      .setLinkNames(true)
+      .setUnfurlLinks(false)
+      .setUnfurlMedia(false)
+      .setReplyBroadcast(true)
+      .build();
+
+    JsonNode json = serialize(params);
+
+    assertThat(json.get("channel").asText()).isEqualTo(CHANNEL_ID);
+    assertThat(json.get("thread_ts").asText()).isEqualTo(THREAD_TS);
+    assertThat(json.get("username").asText()).isEqualTo(USERNAME);
+    assertThat(json.get("icon_emoji").asText()).isEqualTo(":robot_face:");
+    assertThat(json.get("icon_url").asText()).isEqualTo("https://example.com/icon.png");
+    assertThat(json.get("link_names").asBoolean()).isTrue();
+    assertThat(json.get("unfurl_links").asBoolean()).isFalse();
+    assertThat(json.get("unfurl_media").asBoolean()).isFalse();
+    assertThat(json.get("reply_broadcast").asBoolean()).isTrue();
+  }
+
+  @Test
+  public void itKeepsEmptyCollectionsForRequiredFields() throws IOException {
+    ChatPostMessageParams params = ChatPostMessageParams
+      .builder()
+      .setChannelId(CHANNEL_ID)
+      .setText("post message test")
+      .build();
+
+    JsonNode json = serialize(params);
+
+    assertThat(json.get("blocks").isArray()).isTrue();
+    assertThat(json.get("attachments").isArray()).isTrue();
+  }
+
+  @Test
+  public void itOmitsUnsetOptionalFieldsForSlashCommandResponses() throws IOException {
+    SlashCommandResponseParams params = SlashCommandResponseParams
+      .builder()
+      .setChannelId(CHANNEL_ID)
+      .setText("slash command response")
+      .build();
+
+    JsonNode json = serialize(params);
+
+    assertThat(json.has("username")).isFalse();
+    assertThat(json.toString()).doesNotContain(":null");
+    assertThat(json.has("response_type")).isTrue();
+  }
+
+  private static JsonNode serialize(Object params) throws IOException {
+    return ObjectMapperUtils
+      .mapper()
+      .readTree(ObjectMapperUtils.mapper().writeValueAsString(params));
+  }
+}