suppress warning to support testing

Author: Jonopono123

gp2gp-translator/src/main/java/uk/nhs/adaptors/pss/translator/storage/AzureStorageService.java

@@ -4,15 +4,16 @@
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
-import java.util.Base64;
 import java.util.Locale;
 
 import com.azure.storage.blob.BlobContainerClient;
 import com.azure.storage.blob.BlobServiceClient;
 import com.azure.storage.blob.BlobServiceClientBuilder;
 import com.azure.storage.blob.specialized.BlockBlobClient;
 import com.azure.storage.common.StorageSharedKeyCredential;
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 
+@SuppressFBWarnings(value = "EI_EXPOSE_REP2", justification = "BlobServiceClient is immutable and thread-safe.")
 public class AzureStorageService implements StorageService {
 
     // Consistent objects