core/src/main/java/com/twitter/elephantbird/util/ThriftToDynamicProto.java
private String mapProtoMessageType(TStructDescriptor descriptor, Field field) {
    return String.format("%s_%s", protoMessageType(descriptor.getThriftClass()), field.getName());
  }
private String mapProtoMessageType(TStructDescriptor descriptor, Field field) {
    return String.format("%s_%s", protoMessageType(descriptor.getThriftClass()), field.getName());
  }
name the proto message used for Map types after the thrift class name of the enclosing
struct and the field name