diff --git a/contrib/sarvam-ai/pom.xml b/contrib/sarvam-ai/pom.xml
index 0c32593f0..199d0222a 100644
--- a/contrib/sarvam-ai/pom.xml
+++ b/contrib/sarvam-ai/pom.xml
@@ -20,7 +20,7 @@
     <parent>
         <groupId>com.google.adk</groupId>
         <artifactId>google-adk-parent</artifactId>
-        <version>1.1.0</version><!-- {x-version-update:google-adk:current} -->
+        <version>1.3.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
         <relativePath>../../pom.xml</relativePath>
     </parent>
 
diff --git a/core/src/test/java/com/google/adk/models/GeminiLlmConnectionTest.java b/core/src/test/java/com/google/adk/models/GeminiLlmConnectionTest.java
index a3ac09fe5..d031572aa 100644
--- a/core/src/test/java/com/google/adk/models/GeminiLlmConnectionTest.java
+++ b/core/src/test/java/com/google/adk/models/GeminiLlmConnectionTest.java
@@ -21,7 +21,6 @@
 import com.google.common.collect.ImmutableList;
 import com.google.genai.types.Content;
 import com.google.genai.types.FunctionCall;
-import com.google.genai.types.GenerateContentResponseUsageMetadata;
 import com.google.genai.types.LiveServerContent;
 import com.google.genai.types.LiveServerMessage;
 import com.google.genai.types.LiveServerSetupComplete;
@@ -29,8 +28,7 @@
 import com.google.genai.types.LiveServerToolCallCancellation;
 import com.google.genai.types.Part;
 import com.google.genai.types.UsageMetadata;
-import io.reactivex.rxjava3.observers.TestObserver;
-import java.util.List;
+import java.util.Optional;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -48,14 +46,11 @@ public void convertToServerResponse_withInterruptedTrue_mapsInterruptedField() {
             .build();
 
     LiveServerMessage message = LiveServerMessage.builder().serverContent(serverContent).build();
-    TestObserver<LlmResponse> testObserver = new TestObserver<>();
 
-    GeminiLlmConnection.convertToServerResponse(message).subscribe(testObserver);
-
-    testObserver.assertValueCount(1);
-    testObserver.assertComplete();
-    LlmResponse response = testObserver.values().get(0);
+    Optional<LlmResponse> result = GeminiLlmConnection.convertToServerResponse(message);
 
+    assertThat(result.isPresent()).isTrue();
+    LlmResponse response = result.get();
     assertThat(response.content()).isPresent();
     assertThat(response.content().get().text()).isEqualTo("Model response");
     assertThat(response.partial()).hasValue(true);
@@ -74,13 +69,10 @@ public void convertToServerResponse_withInterruptedFalse_mapsInterruptedField()
 
     LiveServerMessage message = LiveServerMessage.builder().serverContent(serverContent).build();
 
-    TestObserver<LlmResponse> testObserver = new TestObserver<>();
-
-    GeminiLlmConnection.convertToServerResponse(message).subscribe(testObserver);
+    Optional<LlmResponse> result = GeminiLlmConnection.convertToServerResponse(message);
 
-    testObserver.assertValueCount(1);
-    testObserver.assertComplete();
-    LlmResponse response = testObserver.values().get(0);
+    assertThat(result.isPresent()).isTrue();
+    LlmResponse response = result.get();
     assertThat(response.interrupted()).hasValue(false);
     assertThat(response.turnComplete()).hasValue(false);
   }
@@ -95,13 +87,10 @@ public void convertToServerResponse_withoutInterruptedField_mapsEmptyOptional()
 
     LiveServerMessage message = LiveServerMessage.builder().serverContent(serverContent).build();
 
-    TestObserver<LlmResponse> testObserver = new TestObserver<>();
-
-    GeminiLlmConnection.convertToServerResponse(message).subscribe(testObserver);
+    Optional<LlmResponse> result = GeminiLlmConnection.convertToServerResponse(message);
 
-    testObserver.assertValueCount(1);
-    testObserver.assertComplete();
-    LlmResponse response = testObserver.values().get(0);
+    assertThat(result.isPresent()).isTrue();
+    LlmResponse response = result.get();
     assertThat(response.interrupted()).isEmpty();
     assertThat(response.turnComplete()).hasValue(true);
   }
@@ -116,13 +105,10 @@ public void convertToServerResponse_withTurnCompleteTrue_mapsPartialFalse() {
 
     LiveServerMessage message = LiveServerMessage.builder().serverContent(serverContent).build();
 
-    TestObserver<LlmResponse> testObserver = new TestObserver<>();
+    Optional<LlmResponse> result = GeminiLlmConnection.convertToServerResponse(message);
 
-    GeminiLlmConnection.convertToServerResponse(message).subscribe(testObserver);
-
-    testObserver.assertValueCount(1);
-    testObserver.assertComplete();
-    LlmResponse response = testObserver.values().get(0);
+    assertThat(result.isPresent()).isTrue();
+    LlmResponse response = result.get();
     assertThat(response.partial()).hasValue(false);
     assertThat(response.turnComplete()).hasValue(true);
   }
@@ -137,13 +123,10 @@ public void convertToServerResponse_withTurnCompleteFalse_mapsPartialTrue() {
 
     LiveServerMessage message = LiveServerMessage.builder().serverContent(serverContent).build();
 
-    TestObserver<LlmResponse> testObserver = new TestObserver<>();
-
-    GeminiLlmConnection.convertToServerResponse(message).subscribe(testObserver);
+    Optional<LlmResponse> result = GeminiLlmConnection.convertToServerResponse(message);
 
-    testObserver.assertValueCount(1);
-    testObserver.assertComplete();
-    LlmResponse response = testObserver.values().get(0);
+    assertThat(result.isPresent()).isTrue();
+    LlmResponse response = result.get();
     assertThat(response.partial()).hasValue(true);
     assertThat(response.turnComplete()).hasValue(false);
   }
@@ -156,13 +139,10 @@ public void convertToServerResponse_withToolCall_mapsContentWithFunctionCall() {
 
     LiveServerMessage message = LiveServerMessage.builder().toolCall(toolCall).build();
 
-    TestObserver<LlmResponse> testObserver = new TestObserver<>();
-
-    GeminiLlmConnection.convertToServerResponse(message).subscribe(testObserver);
+    Optional<LlmResponse> result = GeminiLlmConnection.convertToServerResponse(message);
 
-    testObserver.assertValueCount(1);
-    testObserver.assertComplete();
-    LlmResponse response = testObserver.values().get(0);
+    assertThat(result.isPresent()).isTrue();
+    LlmResponse response = result.get();
     assertThat(response.content()).isPresent();
     assertThat(response.content().get().parts()).isPresent();
     assertThat(response.content().get().parts().get()).hasSize(1);
@@ -172,7 +152,7 @@ public void convertToServerResponse_withToolCall_mapsContentWithFunctionCall() {
   }
 
   @Test
-  public void convertToServerResponse_withUsageMetadata_mapsGenerateResponseUsageMetadata() {
+  public void convertToServerResponse_withUsageMetadata_returnsEmpty() {
     LiveServerMessage message =
         LiveServerMessage.builder()
             .usageMetadata(
@@ -183,68 +163,52 @@ public void convertToServerResponse_withUsageMetadata_mapsGenerateResponseUsageM
                     .build())
             .build();
 
-    TestObserver<LlmResponse> testObserver = new TestObserver<>();
+    Optional<LlmResponse> result = GeminiLlmConnection.convertToServerResponse(message);
 
-    GeminiLlmConnection.convertToServerResponse(message).subscribe(testObserver);
-    testObserver.assertValueCount(1);
-    testObserver.assertComplete();
-    LlmResponse response = testObserver.values().get(0);
-    assertThat(response.usageMetadata()).isPresent();
-    GenerateContentResponseUsageMetadata expectedUsageMetadata =
-        GenerateContentResponseUsageMetadata.builder()
-            .promptTokenCount(10)
-            .candidatesTokenCount(20)
-            .totalTokenCount(30)
-            .build();
-    assertThat(response.usageMetadata()).hasValue(expectedUsageMetadata);
+    assertThat(result.isPresent()).isFalse();
   }
 
   @Test
-  public void convertToServerResponse_withToolCallCancellation_returnsNoValues() {
+  public void convertToServerResponse_withToolCallCancellation_returnsInterrupted() {
     LiveServerMessage message =
         LiveServerMessage.builder()
             .toolCallCancellation(LiveServerToolCallCancellation.builder().build())
             .build();
 
-    TestObserver<LlmResponse> testObserver = new TestObserver<>();
+    Optional<LlmResponse> result = GeminiLlmConnection.convertToServerResponse(message);
 
-    GeminiLlmConnection.convertToServerResponse(message).subscribe(testObserver);
-    testObserver.assertNoValues();
-    testObserver.assertComplete();
+    assertThat(result.isPresent()).isTrue();
+    LlmResponse response = result.get();
+    assertThat(response.interrupted()).hasValue(true);
+    assertThat(response.turnComplete()).hasValue(true);
   }
 
   @Test
-  public void convertToServerResponse_withSetupComplete_returnsNoValues() {
+  public void convertToServerResponse_withSetupComplete_returnsEmpty() {
     LiveServerMessage message =
         LiveServerMessage.builder()
             .setupComplete(LiveServerSetupComplete.builder().build())
             .build();
 
-    TestObserver<LlmResponse> testObserver = new TestObserver<>();
-
-    GeminiLlmConnection.convertToServerResponse(message).subscribe(testObserver);
+    Optional<LlmResponse> result = GeminiLlmConnection.convertToServerResponse(message);
 
-    testObserver.assertNoValues();
-    testObserver.assertComplete();
+    assertThat(result.isPresent()).isFalse();
   }
 
   @Test
   public void convertToServerResponse_withUnknownMessage_returnsErrorResponse() {
     LiveServerMessage message = LiveServerMessage.builder().build();
 
-    TestObserver<LlmResponse> testObserver = new TestObserver<>();
+    Optional<LlmResponse> result = GeminiLlmConnection.convertToServerResponse(message);
 
-    GeminiLlmConnection.convertToServerResponse(message).subscribe(testObserver);
-
-    testObserver.assertValueCount(1);
-    testObserver.assertComplete();
-    LlmResponse response = testObserver.values().get(0);
+    assertThat(result.isPresent()).isTrue();
+    LlmResponse response = result.get();
     assertThat(response.errorCode()).isPresent();
     assertThat(response.errorMessage()).hasValue("Received unknown server message.");
   }
 
   @Test
-  public void convertToServerResponse_withContentAndUsageMetadata_emitsMultiple() {
+  public void convertToServerResponse_withContentAndUsageMetadata_returnsContentOnly() {
     LiveServerContent serverContent =
         LiveServerContent.builder()
             .modelTurn(Content.fromParts(Part.fromText("Model response")))
@@ -264,31 +228,12 @@ public void convertToServerResponse_withContentAndUsageMetadata_emitsMultiple()
             .usageMetadata(usageMetadata)
             .build();
 
-    TestObserver<LlmResponse> testObserver = new TestObserver<>();
-
-    GeminiLlmConnection.convertToServerResponse(message).subscribe(testObserver);
-
-    testObserver.assertValueCount(2);
-    testObserver.assertComplete();
+    Optional<LlmResponse> result = GeminiLlmConnection.convertToServerResponse(message);
 
-    List<LlmResponse> responses = testObserver.values();
-
-    // Check for ServerContent response
-    LlmResponse contentResponse = responses.get(0);
-    assertThat(contentResponse.content()).isPresent();
-    assertThat(contentResponse.content().get().text()).isEqualTo("Model response");
-    assertThat(contentResponse.usageMetadata()).isEmpty();
-
-    // Check for UsageMetadata response
-    LlmResponse usageResponse = responses.get(1);
-    assertThat(usageResponse.content()).isEmpty();
-    assertThat(usageResponse.usageMetadata()).isPresent();
-    GenerateContentResponseUsageMetadata expectedUsageMetadata =
-        GenerateContentResponseUsageMetadata.builder()
-            .promptTokenCount(10)
-            .candidatesTokenCount(20)
-            .totalTokenCount(30)
-            .build();
-    assertThat(usageResponse.usageMetadata()).hasValue(expectedUsageMetadata);
+    assertThat(result.isPresent()).isTrue();
+    LlmResponse response = result.get();
+    assertThat(response.content()).isPresent();
+    assertThat(response.content().get().text()).isEqualTo("Model response");
+    assertThat(response.turnComplete()).hasValue(true);
   }
 }