SerializationException: This serializer must be used with FirebaseEncoder

[Monabr]

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Hello.

Here code I am using

@Serializable(with = TimestampSerializer::class)
override val serverTime: Timestamp = getDefaultPlatformTimestamp(),

And getting

kotlinx.serialization.SerializationException: This serializer must be used with FirebaseEncoder

Before set data to Firestore I am using Properties.encodeToMap(myClass). I believe here the error is occurs.

What am I doing wrong? Documentations says nothing about this case.