Issue while using beta document source file

[TubbyStubby]

Hi,

I was trying to use workspace documents in user message doing something like this -

    fileBlocks := []anthropic.BetaContentBlockParamUnion{}
	for _, fileId := range fileIds {
		fileBlocks = append(fileBlocks, anthropic.BetaContentBlockParamUnion{
			OfDocument: &anthropic.BetaRequestDocumentBlockParam{
				Source: anthropic.BetaRequestDocumentBlockSourceUnionParam{
					OfFile: &anthropic.BetaFileDocumentSourceParam{
						FileID: fileId,
					},
				},
				CacheControl: anthropic.NewBetaCacheControlEphemeralParam(),
			},
		})
	}

	messages := []anthropic.BetaMessageParam{
		anthropic.NewBetaUserMessage(
			fileBlocks...,
		),
		anthropic.NewBetaUserMessage(anthropic.NewBetaTextBlock(prompt)),
	}

I am getting this error -

{
  type: 'error',
  error: {
    type: 'invalid_request_error',
    message: "messages.0.content.0.document.source: Input tag 'file' found using 'type' does not match any of the expected tags: 'base64', 'content', 'text', 'url'"
  },
  request_id: 'req_011CTR6XtLRRed3fcm7ad2Mr'
}

Is this not supported yet? or should the message be constructed in another way?