@Override
  protected void standardSchemeWriteValue(org.apache.thrift.protocol.TProtocol oprot) throws org.apache.thrift.TException {
    switch (setField_) {
      case INT_VALUE:
        java.lang.Integer intValue = (java.lang.Integer)value_;
        oprot.writeI32(intValue);
        return;
      case LONG_VALUE:
        java.lang.Long longValue = (java.lang.Long)value_;
        oprot.writeI64(longValue);
        return;
      case STRING_VALUE:
        java.lang.String stringValue = (java.lang.String)value_;
        oprot.writeString(stringValue);
        return;
      case DOUBLE_VALUE:
        java.lang.Double doubleValue = (java.lang.Double)value_;
        oprot.writeDouble(doubleValue);
        return;
      case FLAG:
        java.lang.Boolean flag = (java.lang.Boolean)value_;
        oprot.writeBool(flag);
        return;
      case L_STRING:
        java.util.List<java.lang.String> lString = (java.util.List<java.lang.String>)value_;
        {
          oprot.writeListBegin(new org.apache.thrift.protocol.TList(org.apache.thrift.protocol.TType.STRING, lString.size()));
          for (java.lang.String _iter7 : lString)
          {
            oprot.writeString(_iter7);
          }
          oprot.writeListEnd();
        }
        return;
      case UNION_MSTRING_STRING:
        java.util.Map<java.lang.String,java.lang.String> unionMStringString = (java.util.Map<java.lang.String,java.lang.String>)value_;
        {
          oprot.writeMapBegin(new org.apache.thrift.protocol.TMap(org.apache.thrift.protocol.TType.STRING, org.apache.thrift.protocol.TType.STRING, unionMStringString.size()));
          for (java.util.Map.Entry<java.lang.String, java.lang.String> _iter8 : unionMStringString.entrySet())
          {
            oprot.writeString(_iter8.getKey());
            oprot.writeString(_iter8.getValue());
          }
          oprot.writeMapEnd();
        }
        return;
      default:
        throw new java.lang.IllegalStateException("Cannot write union with unknown field " + setField_);
    }
  }
Find the _Fields constant that matches name, or null if its not found.
serde/src/gen/thrift/gen-javabean/org/apache/hadoop/hive/serde2/thrift/test/PropValueUnion.java