upload(contentLength, body, options) {
        return this.client.sendOperationRequest({ contentLength, body, options }, uploadOperationSpec);
    }
The Upload Block Blob operation updates the content of an existing block blob. Updating an existing
block blob overwrites any existing metadata on the blob. Partial updates are not supported with Put
Blob; the content of the existing blob is overwritten with the content of the new blob. To perform a
partial update of the content of a block blob, use the Put Block List operation.
@param contentLength The length of the request.
@param body Initial data
@param options The options parameters.