code: public File createUniqueFile(@NotNull final Transaction txn, @NotNull final String pathPrefix) {
          while (true) {
              try {
                  return createFile(txn, pathPrefix + new Object().hashCode());
              } catch (FileExistsException ignored) {
              }
          }
      }
docs: Creates new {@linkplain File} with unique auto-generated path starting with specified {@code pathPrefix}.
  
  @param txn        {@linkplain Transaction} instance
  @param pathPrefix prefix which the path of the {@linkplain File result} will start from
  @return new {@linkplain File}
  @see File
  @see File#getPath()