private Writable getWritableValue(TypeInfo ti, Timestamp value) {
    return new TimestampWritableV2(
        org.apache.hadoop.hive.common.type.Timestamp.ofEpochMilli(value.getTime(), value.getNanos()));
  }
Unit tests for vector expression writers.
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/expressions/TestVectorExpressionWriters.java