Metadatas values for some reason becomes OracleJsonStringImpl type, and toJson method on OracleVectorStore dont support that.
The metadata is being inserted on db two times, first just the user defined metada, after the user defined metadata and the "distance" metadata. The first one works well, but after is saved just the "distance" because the problem above.
Comment From: angelormar
Apparently the error occurs due to a high case letter. Change the "conversationId" to "conversationid" and its works, I don't know anymore if is a bug or not but that occupied me for a long time...