#vulnerable code 
                              Map<WorkflowInstance, Long> readActiveWorkflowInstances() throws IOException {
    final Table activeStatesTable = connection.getTable(ACTIVE_STATES_TABLE_NAME);
    final ImmutableMap.Builder<WorkflowInstance, Long> map = ImmutableMap.builder();

    for (Result result : activeStatesTable.getScanner(STATE_CF, STATE_QUALIFIER)) {
      final WorkflowInstance workflowInstance =
          WorkflowInstance.parseKey(Bytes.toString(result.getRow()));
      final long counter = Long.parseLong(Bytes.toString(result.value()));

      map.put(workflowInstance, counter);
    }

    return map.build();
  } 
                            #location 1 
                            #vulnerability type CHECKERS_IMMUTABLE_CAST
#fixed code
                              BigtableStorage(Connection connection, Duration retryBaseDelay) {
    this.connection = Objects.requireNonNull(connection);
    this.retryBaseDelay = Objects.requireNonNull(retryBaseDelay);
  }