Fix string comparison in S3 client (#3875) [ci fast]

Signed-off-by: Ben Sherman <[email protected]>
Co-authored-by: Paolo Di Tommaso <[email protected]>

plugins/nf-amazon/src/main/nextflow/cloud/aws/nio/S3Client.java

@@ -583,7 +583,7 @@ protected void restoreFromGlacier(String bucketName, String key) {
 			RestoreObjectRequest request = new RestoreObjectRequest(bucketName, key);
 
 			String storageClass = client.getObjectMetadata(bucketName, key).getStorageClass();
-			if( storageClass != "INTELLIGENT_TIERING" )
+			if( storageClass!=null && !storageClass.equals("INTELLIGENT_TIERING") )
 				request.setExpirationInDays(glacierExpirationDays);
 
 			if( glacierRetrievalTier != null )