opentelemetry-exporter-otlp does not work with protobuf 4.x

[thatsdone]

Hi, I think now we need to explicitly specify version of protobuf pip package that is used from opentelemetry-exporter-otlp.

Reasonable resolution would be noting this topic somewhere in the documentation, IMHO.

Describe your environment

• Ubuntu 20.04 or 22.04 (docker image)
• Python 3.8.10 (Ubuntu 20.04) or Python 3.10.4 (Ubuntu 22.04)
• opentelemetry 1.11.1 (also tried 1.9.1)
• protobuf 4.21.2 (current latest release at pypi.org)

Steps to reproduce

You would see a stack trace like below so far as the installed protobuf version is 4.x.
At least, protobuf 3.20.1 (current latest 3.x series release) works.

# python3 test1.py
Traceback (most recent call last):
  File "test1.py", line 40, in <module>
    from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import OTLPSpanExporter
  File "/usr/local/lib/python3.8/dist-packages/opentelemetry/exporter/otlp/proto/grpc/trace_exporter/__init__.py", line 22, in <module>
    from opentelemetry.exporter.otlp.proto.grpc.exporter import (
  File "/usr/local/lib/python3.8/dist-packages/opentelemetry/exporter/otlp/proto/grpc/exporter.py", line 39, in <module>
    from opentelemetry.proto.common.v1.common_pb2 import (
  File "/usr/local/lib/python3.8/dist-packages/opentelemetry/proto/common/v1/common_pb2.py", line 36, in <module>
    _descriptor.FieldDescriptor(
  File "/usr/local/lib/python3.8/dist-packages/google/protobuf/descriptor.py", line 560, in __new__
    _message.Message._CheckCalledFromGeneratedFile()
TypeError: Descriptors cannot not be created directly.
If this call came from a _pb2.py file, your generated code is out of date and must be regenerated with protoc >= 3.19.0.
If you cannot immediately regenerate your protos, some other possible workarounds are:
 1. Downgrade the protobuf package to 3.20.x or lower.
 2. Set PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=python (but this will use pure-Python parsing and will be much slower).

More information: https://developers.google.com/protocol-buffers/docs/news/2022-05-06#python-updates

What is the expected behavior?

No stack trace.

What is the actual behavior?

OTEL client program works w/o the stacktrace.

[srikanthccv]

Duplicate of #2717