pig/src/main/java/com/twitter/elephantbird/pig/util/PigToProtobuf.java
public static Message tupleToMessage(Builder builder, Tuple tuple) {
    return tupleToMessage(builder, builder.getDescriptorForType().getFields(), tuple);
  }
public static Message tupleToMessage(Builder builder, Tuple tuple) {
    return tupleToMessage(builder, builder.getDescriptorForType().getFields(), tuple);
  }
Turn a Tuple into a Message with the given type.
@param builder a builder for the Message type the tuple will be converted to
@param tuple the tuple
@return a message representing the given tuple