what is the meaning of "Value" class in .proto file

Question

can someone please explain me the meaning of "Value" in below .proto file?

message Test {
string id = 1;
string name = 2;
google.protobuf.Value property = 6;}

Answer 1

Without an import it probably shouldn't work, however: it represents a flexibly typed value; the Value "well known type" is essentially a union (oneof) of a few common types, with the Java API (from your tags) described here.

The definition is in struct.proto (hence you'll need import "google/protobuf/struct.proto";), or basically:

message Value {
  // The kind of value.
  oneof kind {
    // Represents a null value.
    NullValue null_value = 1;
    // Represents a double value.
    double number_value = 2;
    // Represents a string value.
    string string_value = 3;
    // Represents a boolean value.
    bool bool_value = 4;
    // Represents a structured value.
    Struct struct_value = 5;
    // Represents a repeated `Value`.
    ListValue list_value = 6;
  }
}