checksumSHA1

This header can be used as a data integrity check to verify that the data received is the same data that was originally sent. This specifies the base64-encoded, 160-bit SHA-1 digest of the object returned by the Object Lambda function. This may not match the checksum for the object stored in Amazon S3. Amazon S3 will perform validation of the checksum values only when the original GetObject request required checksum validation. For more information about checksums, see Checking object integrity in the Amazon S3 User Guide. Only one checksum header can be specified at a time. If you supply multiple checksum headers, this request will fail.

SotoS3Types.swift:9799
let checksumSHA1: String?