Fix format and add tests

Author: rlazo

firebase-ai/src/main/kotlin/com/google/firebase/ai/type/ThinkingConfig.kt

@@ -47,7 +47,8 @@ private constructor(
       this.includeThoughts = includeThoughts
     }
 
-    public fun build(): ThinkingConfig = ThinkingConfig(thinkingBudget = thinkingBudget)
+    public fun build(): ThinkingConfig =
+      ThinkingConfig(thinkingBudget = thinkingBudget, includeThoughts = includeThoughts)
   }
 
   internal fun toInternal() = Internal(thinkingBudget, includeThoughts)

firebase-ai/src/test/java/com/google/firebase/ai/type/ThinkingConfigTest.kt

@@ -39,6 +39,21 @@ internal class ThinkingConfigTest {
     Json.encodeToString(thinkingConfig.toInternal()).shouldEqualJson(expectedJson)
   }
 
+  @Test
+  fun `Include though thinkingConfig`() {
+    val thinkingConfig = ThinkingConfig.Builder().setIncludeThoughts(true).build()
+    // CamelCase or snake_case work equally fine
+    val expectedJson =
+      """
+      {
+          "includeThoughts": true
+      }
+      """
+        .trimIndent()
+
+    Json.encodeToString(thinkingConfig.toInternal()).shouldEqualJson(expectedJson)
+  }
+
   @Test
   fun `thinkingConfig DSL correctly delegates to ThinkingConfig#Builder`() {
     val thinkingConfig = ThinkingConfig.Builder().setThinkingBudget(1024).build()