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Thank you!

Describe the bug
A clear and concise description of what the bug is.

PineconeEmbeddingStore, the Pinecone implementation of Embedding store, is a TextSegment embeddings store. Since the latter has a Metadata attribute, it stands to reason that if a client called the add method using TextSegments with metadata, that the metadata would be uploaded to Pinecone. The actual behavior is that the Metadata gets dropped.

Log and Stack trace
Please provide a log and a stack trace (with exception), if applicable.

N/A

To Reproduce
Please provide a relevant code snippets to reproduce this bug.

1. Instantiate a Pinecone Client, index, and an embedding model
2. Create a TextSegment with non-trivial metadata, for example

(excuse my Java, I am a Clojure programmer)

Metadata m = new Metadata(Map.of(
    "a", "b",
    "c", "d"
));

TextSegment t = TextSegment.from("I Am a text segment, m)

3. Create embeddings for this text (although you can actually pass in a random vector for this repro) and invoke .add with the segment to upload to Pinecone
4. The metadata will not make it to Pinecone

Expected behavior
A clear and concise description of what you expected to happen.
Expecting the metadata to appear in the Pinecone console/be retrieved with Query requests

Please complete the following information:

• LangChain4j version: e.g. 0.24.0
• Java version:o openjdk version "21.0.1" 2023-10-17
• Spring Boot version (if applicable): e.g. 2.7.14

Additional context
Add any other context about the problem here.
This appears to be just omitted from the interaction with Pinecone:

I may try to make a pull request. In the meantime I will have to write my own Pinecone integration with their SDK.