S3_MIMEType.java

//AWS SDK 1.x.x
final PutObjectRequest putRequest = new PutObjectRequest(s3bucket, targetDirectory + “/” + file.getName(), file).withCannedAcl(CannedAccessControlList.PublicRead);
final Upload upload = transferManager.upload(putRequest);

//AWS SDK 2.0 — with ContentType 
String fileType = Files.probeContentType(file);
final S3Client s3client;
s3client.putObject(PutObjectRequest.builder().bucket(s3bucket).key(targetDirectory + FileSystems.getDefault().getSeparator() + file.getFileName()).acl(ObjectCannedACL.PUBLIC_READ).contentType(fileType).build(),RequestBody.of(file));