in api/src/main/scala/com/gu/core/store/store.scala [257:265]
private[this] def objectMetadata(avatarId: UUID, user: User, originalFilename: String, mimeType: String): ObjectMetadata = {
val metadata = new ObjectMetadata()
metadata.addUserMetadata("avatar-id", avatarId.toString)
metadata.addUserMetadata("user-id", user.toString)
metadata.addUserMetadata("original-filename", EscapedUnicode(originalFilename))
metadata.setCacheControl("max-age=3600")
metadata.setContentType(mimeType)
metadata
}