verify existent storage path in createBinary. (#3610)

Author: eduardojst10

roda-core/roda-core/src/main/java/org/roda/core/storage/DefaultTransactionalStorageService.java

@@ -290,6 +290,11 @@ public Binary createBinary(StoragePath storagePath, ContentPayload payload, bool
     NotFoundException {
     TransactionalStoragePathOperationLog operationLog;
     // if storage path is agent we need to register a create or update operation
+
+    if (mainStorageService.exists(storagePath)) {
+      throw new AlreadyExistsException("Binary already exists: " + storagePath);
+    }
+
     if (storagePath.getDirectoryPath() != null && !storagePath.getDirectoryPath().isEmpty()
       && storagePath.getDirectoryPath().getFirst().equals(RodaConstants.STORAGE_DIRECTORY_AGENTS)) {
       operationLog = registerOperation(storagePath, OperationType.CREATE_OR_UPDATE);