@Override
  public String vectorExpressionParameters() {
    StringBuilder sb = new StringBuilder();
    sb.append("col ");
    sb.append(inputCol);
    sb.append(", values ");
    sb.append(displayArrayOfUtf8ByteArrays(inListValues));
    return sb.toString();
  }
After construction you must call setInListValues() to add the values to the IN set.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/FilterStringColumnInList.java