Used to specify a previously created context cache to use with generation. For Vertex, this should be of the form: "projects/PROJECT_NUMBER/locations/LOCATION/cachedContents/CACHE_ID",
See these guides for more information on how to use context caching: https://cloud.google.com/vertex-ai/generative-ai/docs/context-cache/context-cache-create https://cloud.google.com/vertex-ai/generative-ai/docs/context-cache/context-cache-use
cachedContent: string