Repository: open-telemetry/opentelemetry-python

Issue:
Consider renaming BaggagePropagator
BaggagePropagator is probably a too-generic name. In contrast, there's `TraceContextTextMapPropagator`, so maybe renaming it to something along those lines could convey more clarity.


Discussion:
Would `W3CBaggagePropagator` be sufficient? It is what [Java](https://github.com/open-telemetry/opentelemetry-java/blob/4623334c7c5fc524f19c544a38864478d6b2c757/api/all/src/main/java/io/opentelemetry/api/baggage/propagation/W3CBaggagePropagator.java#L24) is doing.
Yes, that would work :)
Is this defined in the spec? i'm seeing that every implementation seems to have a different name for it, js calls is `HttpBaggage` and go appears to call it simply `Baggage` https://github.com/open-telemetry/opentelemetry-go/blob/ecf65d7968225482a4d50e4955d6bc826119b49c/propagation/baggage.go#L28
Oh definitely too many names :) I'd vow specifically and specially **against** `BaggagePropagator` as it's too generic (will fill an issue for that in the Go SIG). 

Resolving patch:
diff --git a/opentelemetry-api/src/opentelemetry/baggage/propagation/__init__.py b/opentelemetry-api/src/opentelemetry/baggage/propagation/__init__.py
--- a/opentelemetry-api/src/opentelemetry/baggage/propagation/__init__.py
+++ b/opentelemetry-api/src/opentelemetry/baggage/propagation/__init__.py
@@ -21,7 +21,7 @@
 from opentelemetry.propagators import textmap
 
 
-class BaggagePropagator(textmap.TextMapPropagator):
+class W3CBaggagePropagator(textmap.TextMapPropagator):
     """Extracts and injects Baggage which is used to annotate telemetry."""
 
     MAX_HEADER_LENGTH = 8192
diff --git a/opentelemetry-api/src/opentelemetry/propagate/__init__.py b/opentelemetry-api/src/opentelemetry/propagate/__init__.py
--- a/opentelemetry-api/src/opentelemetry/propagate/__init__.py
+++ b/opentelemetry-api/src/opentelemetry/propagate/__init__.py
@@ -25,7 +25,7 @@
 ``opentelemetry.propagators.composite.CompositeHTTPPropagator`` with 2
 propagators, one of type
 ``opentelemetry.trace.propagation.tracecontext.TraceContextTextMapPropagator``
-and other of type ``opentelemetry.baggage.propagation.BaggagePropagator``.
+and other of type ``opentelemetry.baggage.propagation.W3CBaggagePropagator``.
 Notice that these propagator classes are defined as
 ``opentelemetry_propagator`` entry points in the ``setup.cfg`` file of
 ``opentelemetry``.


Test patch:
diff --git a/opentelemetry-api/tests/baggage/test_baggage_propagation.py b/opentelemetry-api/tests/baggage/test_baggage_propagation.py
--- a/opentelemetry-api/tests/baggage/test_baggage_propagation.py
+++ b/opentelemetry-api/tests/baggage/test_baggage_propagation.py
@@ -16,7 +16,7 @@
 from unittest.mock import Mock, patch
 
 from opentelemetry import baggage
-from opentelemetry.baggage.propagation import BaggagePropagator
+from opentelemetry.baggage.propagation import W3CBaggagePropagator
 from opentelemetry.context import get_current
 from opentelemetry.propagators.textmap import DictGetter
 
@@ -25,7 +25,7 @@
 
 class TestBaggagePropagation(unittest.TestCase):
     def setUp(self):
-        self.propagator = BaggagePropagator()
+        self.propagator = W3CBaggagePropagator()
 
     def _extract(self, header_value):
         """Test helper"""
@@ -87,7 +87,7 @@ def test_invalid_header(self):
         self.assertEqual(self._extract(header), expected)
 
     def test_header_too_long(self):
-        long_value = "s" * (BaggagePropagator.MAX_HEADER_LENGTH + 1)
+        long_value = "s" * (W3CBaggagePropagator.MAX_HEADER_LENGTH + 1)
         header = "key1={}".format(long_value)
         expected = {}
         self.assertEqual(self._extract(header), expected)
@@ -96,15 +96,15 @@ def test_header_contains_too_many_entries(self):
         header = ",".join(
             [
                 "key{}=val".format(k)
-                for k in range(BaggagePropagator.MAX_PAIRS + 1)
+                for k in range(W3CBaggagePropagator.MAX_PAIRS + 1)
             ]
         )
         self.assertEqual(
-            len(self._extract(header)), BaggagePropagator.MAX_PAIRS
+            len(self._extract(header)), W3CBaggagePropagator.MAX_PAIRS
         )
 
     def test_header_contains_pair_too_long(self):
-        long_value = "s" * (BaggagePropagator.MAX_PAIR_LENGTH + 1)
+        long_value = "s" * (W3CBaggagePropagator.MAX_PAIR_LENGTH + 1)
         header = "key1=value1,key2={},key3=value3".format(long_value)
         expected = {"key1": "value1", "key3": "value3"}
         self.assertEqual(self._extract(header), expected)
diff --git a/opentelemetry-api/tests/propagators/test_propagators.py b/opentelemetry-api/tests/propagators/test_propagators.py
--- a/opentelemetry-api/tests/propagators/test_propagators.py
+++ b/opentelemetry-api/tests/propagators/test_propagators.py
@@ -17,7 +17,7 @@
 from unittest import TestCase
 from unittest.mock import Mock, patch
 
-from opentelemetry.baggage.propagation import BaggagePropagator
+from opentelemetry.baggage.propagation import W3CBaggagePropagator
 from opentelemetry.environment_variables import OTEL_PROPAGATORS
 from opentelemetry.trace.propagation.tracecontext import (
     TraceContextTextMapPropagator,
@@ -33,7 +33,8 @@ def test_propagators(propagators):
 
             self.assertEqual(len(propagators), 2)
             self.assertEqual(
-                propagators, {TraceContextTextMapPropagator, BaggagePropagator}
+                propagators,
+                {TraceContextTextMapPropagator, W3CBaggagePropagator},
             )
 
         mock_compositehttppropagator.configure_mock(