Can't cache just the system prompt TypeError: value must not be empty

[DreamGenX]

Caching just the system prompt is not supported. This would be extremely useful.

import vertexai
import datetime

from vertexai.generative_models import Part
from vertexai.preview import caching

vertexai.init(project=PROJECT_ID, location="us-central1")

system_instruction = """
You are an expert researcher. You always stick to the facts in the sources provided, and never make up new facts.
Now look at these research papers, and answer the following questions.
"""

cached_content = caching.CachedContent.create(
    model_name="gemini-1.5-pro-002",
    system_instruction=system_instruction * 2000,
    # contents=[],
    ttl=datetime.timedelta(minutes=1),
    display_name="example-cache",
)

This results in:

TypeError: value must not be empty

Version info:

Name: google-cloud-aiplatform
Version: 1.71.1
Summary: Vertex AI API client library
Home-page: https://github.com/googleapis/python-aiplatform
Author: Google LLC
Author-email: [email protected]
License: Apache 2.0
Location: xxx
Requires: docstring-parser, google-api-core, google-auth, google-cloud-bigquery, google-cloud-resource-manager, google-cloud-storage, packaging, proto-plus, protobuf, pydantic, shapely
Required-by: vertexai