make FunctionCall.args nullable

.changes/common/coach-cap-control-dinosaurs.json

@@ -0,0 +1 @@
+{"type":"MINOR","changes":["make FunctionCall.args nullable"]}

.changes/generativeai/board-burn-cushion-calculator.json

@@ -0,0 +1 @@
+{"type":"MAJOR","changes":["make FunctionCallPart.args nullable"]}

common/src/main/kotlin/com/google/ai/client/generativeai/common/shared/Types.kt

@@ -64,7 +64,7 @@ data class CodeExecutionResultPart(val codeExecutionResult: CodeExecutionResult)
 
 @Serializable data class FunctionResponse(val name: String, val response: JsonObject)
 
-@Serializable data class FunctionCall(val name: String, val args: Map<String, String?>)
+@Serializable data class FunctionCall(val name: String, val args: Map<String, String?>? = null)
 
 @Serializable data class FileDataPart(@SerialName("file_data") val fileData: FileData) : Part
 

common/src/test/java/com/google/ai/client/generativeai/common/UnarySnapshotTests.kt

@@ -316,7 +316,8 @@ internal class UnarySnapshotTests {
         val response = apiController.generateContent(textGenerateContentRequest("prompt"))
         val callPart = (response.candidates!!.first().content!!.parts.first() as FunctionCallPart)
 
-        callPart.functionCall.args["season"] shouldBe null
+        callPart.functionCall.args shouldNotBe null
+        callPart.functionCall.args?.get("season") shouldBe null
       }
     }
 
@@ -333,7 +334,22 @@ internal class UnarySnapshotTests {
             it.parts.first().shouldBeInstanceOf<FunctionCallPart>()
           }
 
-        callPart.functionCall.args["current"] shouldBe "true"
+        callPart.functionCall.args shouldNotBe null
+        callPart.functionCall.args?.get("current") shouldBe "true"
+      }
+    }
+
+  @Test
+  fun `function call has no arguments field`() =
+    goldenUnaryFile("success-function-call-empty-arguments.json") {
+      withTimeout(testTimeout) {
+        val response = apiController.generateContent(textGenerateContentRequest("prompt"))
+        val content = response.candidates.shouldNotBeNullOrEmpty().first().content
+        content.shouldNotBeNull()
+        val callPart = content.parts.shouldNotBeNullOrEmpty().first() as FunctionCallPart
+
+        callPart.functionCall.name shouldBe "current_time"
+        callPart.functionCall.args shouldBe null
       }
     }
 

common/src/test/resources/golden-files/unary/success-function-call-empty-arguments.json

@@ -0,0 +1,18 @@
+{
+  "candidates": [
+    {
+      "content": {
+        "parts": [
+          {
+            "functionCall": {
+              "name": "current_time"
+            }
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "index": 0
+    }
+  ]
+}

generativeai/src/main/java/com/google/ai/client/generativeai/type/Part.kt

@@ -53,7 +53,7 @@ class FileDataPart(val uri: String, val mimeType: String) : Part
 fun Part.asFileDataPartOrNull(): FileDataPart? = this as? FileDataPart
 
 /** Represents function call name and params received from requests. */
-class FunctionCallPart(val name: String, val args: Map<String, String?>) : Part
+class FunctionCallPart(val name: String, val args: Map<String, String?>?) : Part
 
 /** Represents function call output to be returned to the model when it requests a function call */
 class FunctionResponsePart(val name: String, val response: JSONObject) : Part

generativeai/src/test/java/com/google/ai/client/generativeai/GenerativeModelTests.kt

@@ -209,8 +209,9 @@ internal class GenerativeModelTests {
     response.functionCalls.firstOrNull()?.let {
       it.shouldNotBeNull()
       it.name shouldBe "getExchangeRate"
-      it.args shouldContain ("currencyFrom" to "USD")
-      it.args shouldContain ("currencyTo" to "EUR")
+      it.args.shouldNotBeNull()
+      it.args?.shouldContain("currencyFrom" to "USD")
+      it.args?.shouldContain("currencyTo" to "EUR")
     }
 
     coEvery { mockApiController.generateContent(any()) } returns