'Adds a v3 Property to an Entity based on information from a v4 Property.
Args:
property_name: the name of the property
is_multi: whether the property contains multiple values
is_projection: whether the property is a projection
v4_value: an entity_v4_pb.Value
v3_entity: an entity_pb.EntityProto'

def __add_v3_property_from_v4(self, property_name, is_multi, is_projection, v4_value, v3_entity):

    if v4_value.indexed():
        self.v4_to_v3_property(property_name, is_multi, is_projection, v4_value, v3_entity.add_property())
    else:
        self.v4_to_v3_property(property_name, is_multi, is_projection, v4_value, v3_entity.add_raw_property())
