code: protected String getSnapshotIdFromProperties(String spaceId) {
          Properties props = new Properties();
          try (InputStream is = this.snapshotProvider.getContent(spaceId, Constants.SNAPSHOT_PROPS_FILENAME)
                                                     .getContentStream()) {
              props.load(is);
              return props.getProperty(Constants.SNAPSHOT_ID_PROP);
          } catch (NotFoundException ex) {
              return null;
          } catch (Exception e) {
              throw new TaskException(
                  MessageFormat.format("Call to create snapshot failed, unable to determine existence of " +
                                       "snapshot properties file in {0}. Error: {1}", spaceId, e.getMessage()));
          }
      }
docs: Returns snapshot from the snapshot properties file if it exists
  
  @param spaceId
  @return snapshot from the snapshot properties file if it exists, otherwise null