Remove search condition from VectorStoreDocumentRetriever

public final class VectorStoreDocumentRetriever implements DocumentRetriever {

private final VectorStore vectorStore;

private final Double similarityThreshold;

private final Integer topK;

private final Supplier<Filter.Expression> filterExpression;

@Override
public List<Document> retrieve(Query query) {
	Assert.notNull(query, "query cannot be null");
	var searchRequest = SearchRequest.builder()
		.query(query.text())
		.filterExpression(this.filterExpression.get())
		.similarityThreshold(this.similarityThreshold)
		.topK(this.topK)
		.build();
	return this.vectorStore.similaritySearch(searchRequest);
}

}

I think that similarityThreshold\topK\filterExpression should be carried by Query. It can make VectorStoreDocumentRetriever be a singleton Object.

Start with VectorStoreDocumentRetriever and its retrieve(Query) method, then compare how Query, SearchRequest, and VectorStore are used in the surrounding code. Determine whether similarityThreshold, topK, and filterExpression should move onto Query and whether the retriever can become a singleton; done means the design is implemented consistently without changing retrieval behavior.