OZG-5636 refactor buildAttachment method

bayernid-proxy-impl/src/main/java/de/ozgcloud/nachrichten/postfach/bayernid/proxy/UploadStreamObserver.java

@@ -47,8 +47,6 @@ import lombok.extern.log4j.Log4j2;
 @RequiredArgsConstructor
 public class UploadStreamObserver implements StreamObserver<GrpcSendBayernIdMessageRequest> {
 
-	static final String ATTACHMENT_FILE_SUFFIX = ".ozg-cloud.tmp";
-
 	private final StreamObserver<GrpcSendBayernIdMessageResponse> responseObserver;
 	private final BayernIdProxyService proxyService;
 	private final BayernIdMessageMapper messageMapper;
@@ -82,15 +80,17 @@ public class UploadStreamObserver implements StreamObserver<GrpcSendBayernIdMess
 	}
 
 	Attachment buildAttachment(GrpcAttachmentMetadata attachmentMetadata) {
+		InputStream temporallyFile;
 		try {
+			temporallyFile = createTemporallyFile();
+		} catch (IOException e) {
+			throw new TechnicalException("Can not create temporary file for attachment " + attachmentMetadata.getFileName(), e);
+		}
 		return Attachment.builder()
 				.name(attachmentMetadata.getFileName())
 				.type(attachmentMetadata.getFileType())
-					.content(createTemporallyFile())
+				.content(temporallyFile)
 				.build();
-		} catch (IOException e) {
-			throw new TechnicalException("Can not create temporary file for attachment " + attachmentMetadata.getFileName(), e);
-		}
 	}
 
 	InputStream createTemporallyFile() throws IOException {