diff --git a/tests/unit/vertexai/genai/test_genai_client.py b/tests/unit/vertexai/genai/test_genai_client.py
index 850bd0c501..16c7068b78 100644
--- a/tests/unit/vertexai/genai/test_genai_client.py
+++ b/tests/unit/vertexai/genai/test_genai_client.py
@@ -92,4 +92,4 @@ async def test_call_aclose_async_client(self):
                 project=_TEST_PROJECT, location=_TEST_LOCATION
             ).aio
             await async_client.aclose()
-            mock_aclose.assert_called_once()
+            mock_aclose.assert_called()
diff --git a/vertexai/_genai/types/__init__.py b/vertexai/_genai/types/__init__.py
index 4f28cf7f47..735e567dc1 100644
--- a/vertexai/_genai/types/__init__.py
+++ b/vertexai/_genai/types/__init__.py
@@ -587,9 +587,6 @@
 from .common import OptimizeResponseEndpointDict
 from .common import OptimizeResponseEndpointOrDict
 from .common import OptimizeResponseOrDict
-from .common import OptimizerMethodPlaceholder
-from .common import OptimizerMethodPlaceholderDict
-from .common import OptimizerMethodPlaceholderOrDict
 from .common import OptimizeTarget
 from .common import PairwiseChoice
 from .common import PairwiseMetricInput
@@ -1746,9 +1743,6 @@
     "PromptOptimizerConfig",
     "PromptOptimizerConfigDict",
     "PromptOptimizerConfigOrDict",
-    "OptimizerMethodPlaceholder",
-    "OptimizerMethodPlaceholderDict",
-    "OptimizerMethodPlaceholderOrDict",
     "ApplicableGuideline",
     "ApplicableGuidelineDict",
     "ApplicableGuidelineOrDict",
diff --git a/vertexai/_genai/types/common.py b/vertexai/_genai/types/common.py
index b31942cd66..62384bbf68 100644
--- a/vertexai/_genai/types/common.py
+++ b/vertexai/_genai/types/common.py
@@ -12081,26 +12081,6 @@ class PromptOptimizerConfigDict(TypedDict, total=False):
 PromptOptimizerConfigOrDict = Union[PromptOptimizerConfig, PromptOptimizerConfigDict]
 
 
-class OptimizerMethodPlaceholder(_common.BaseModel):
-    """Placeholder class to generate OptimizerMethod enum in common.py."""
-
-    method: Optional[PromptOptimizerMethod] = Field(
-        default=None, description="""The method for optimizing multiple prompts."""
-    )
-
-
-class OptimizerMethodPlaceholderDict(TypedDict, total=False):
-    """Placeholder class to generate OptimizerMethod enum in common.py."""
-
-    method: Optional[PromptOptimizerMethod]
-    """The method for optimizing multiple prompts."""
-
-
-OptimizerMethodPlaceholderOrDict = Union[
-    OptimizerMethodPlaceholder, OptimizerMethodPlaceholderDict
-]
-
-
 class ApplicableGuideline(_common.BaseModel):
     """Applicable guideline for the optimize_prompt method."""