TW-3961: include grantID in get folders response

.claude/instructions.md

@@ -9,6 +9,23 @@ Your job is to maintain parity with the API to ensure that the SDK supports all
 
 When asked to add support for a new feature, query parameter, or API endpoint, follow this workflow:
 
+### 0. Analyse Backward Compatibility FIRST (before proposing any plan)
+
+Before writing a plan or touching any code, explicitly analyse whether the proposed changes are backward compatible for existing SDK consumers (both Kotlin and Java).
+
+Check all of the following:
+- **Source compatibility (Kotlin)**: Does changing a type (e.g. `String` → `String?`) break existing call sites that assume non-nullability?
+- **Source compatibility (Java)**: Does the change affect compiled Java code that uses the SDK?
+- **Binary compatibility (JVM)**: Does the bytecode signature of any public method change?
+- **Constructor/data class compatibility**: Does changing a field's type or default break existing construction patterns?
+
+If the change is **NOT** backward compatible, output this warning in your response before anything else:
+
+> # ⚠️ WARNING: THIS CHANGE IS NOT BACKWARD COMPATIBLE ⚠️
+> Existing SDK consumers will be broken. Do not proceed without explicit user approval or a backward-compatible alternative.
+
+If a backward-compatible alternative exists (e.g. using `String = ""` instead of `String?` to keep Moshi happy while preserving non-nullability), prefer it and explain why.
+
 ### 1. Understand the Codebase
 - Scan the project structure
 - Understand the architecture and how it's organized

.claude/settings.local.json

@@ -12,7 +12,9 @@
       "Bash(/usr/libexec/java_home:*)",
       "Bash(./gradlew clean test:*)",
       "Bash(./gradlew:*)",
-      "Bash(./gradlew build:*)"
+      "Bash(./gradlew build:*)",
+      "mcp__claude_ai_Atlassian__getJiraIssue",
+      "WebFetch(domain:developer.nylas.com)"
     ]
   }
 }

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Nylas Java SDK Changelog
 
+## [Unreleased]
+
+### Fixed
+* `Folder.id` and `Folder.grantId` now default to empty strings so deserialization no longer fails when either field is absent from the API response due to the `select` query parameter
+
 ## [v2.15.1] - Release 2026-03-30
 
 ### Changed

src/main/kotlin/com/nylas/models/Folder.kt

@@ -10,12 +10,12 @@ data class Folder(
    * A globally unique object identifier.
    */
   @Json(name = "id")
-  val id: String,
+  val id: String = "",
   /**
    * A Grant ID of the Nylas account.
    */
   @Json(name = "grant_id")
-  val grantId: String,
+  val grantId: String = "",
   /**
    * Folder name
    */

src/test/kotlin/com/nylas/resources/FoldersTests.kt

@@ -75,6 +75,34 @@ class FoldersTests {
       assertEquals(0, folder.totalCount)
       assertEquals(listOf("\\SENT"), folder.attributes)
     }
+
+    @Test
+    fun `Folder deserializes correctly when grant_id is absent due to select`() {
+      val adapter = JsonHelper.moshi().adapter(Folder::class.java)
+      val jsonBuffer = Buffer().writeUtf8(
+        """{ "id": "SENT", "name": "SENT", "object": "folder" }""",
+      )
+
+      val folder = adapter.fromJson(jsonBuffer)!!
+      assertIs<Folder>(folder)
+      assertEquals("SENT", folder.id)
+      assertEquals("", folder.grantId)
+      assertEquals("SENT", folder.name)
+    }
+
+    @Test
+    fun `Folder deserializes correctly when both id and grant_id are absent due to select`() {
+      val adapter = JsonHelper.moshi().adapter(Folder::class.java)
+      val jsonBuffer = Buffer().writeUtf8(
+        """{ "name": "SENT", "object": "folder" }""",
+      )
+
+      val folder = adapter.fromJson(jsonBuffer)!!
+      assertIs<Folder>(folder)
+      assertEquals("", folder.id)
+      assertEquals("", folder.grantId)
+      assertEquals("SENT", folder.name)
+    }
   }
 
   @Nested