feat(core,cli): add support for Gemma 4 models (experimental) (#25604)

packages/a2a-server/src/utils/testing_utils.ts

@@ -112,6 +112,7 @@ export function createMockConfig(
     }),
     isContextManagementEnabled: vi.fn().mockReturnValue(false),
     getContextManagementConfig: vi.fn().mockReturnValue({ enabled: false }),
+    getExperimentalGemma: vi.fn().mockReturnValue(false),
     ...overrides,
   } as unknown as Config;