Support ChatAnthropic for Langchain instrumentation (opentelemetry-instrumentation-langchain)

[salaboy]

Describe your environment

OS: Mac OS
Python version: (e.g., Python 3.14.0)
Package version: @main

What happened?

When trying to use opentelemetry-instrumentation-langchain there is no support for ChatAnthropic hence anthropic users don't get any instrumentation.

Steps to Reproduce

Create a simple application like this one: https://github.com/salaboy/observing-ai/tree/main/python/langchain/python-merch-store-otel-langchain-official using Anthropic, no spans are created for Anthropic.

Expected Result

Instrumented ChatAnthropic

Actual Result

No spans being created for ChatAnthropic.

Additional context

No response

Would you like to implement a fix?

Yes

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