Deprecate trace mutli propagator (#2342)

* add deprecation

* backfill tests

* remove invalid tests

* add @

* Update extensions/trace-propagators/src/main/java/io/opentelemetry/extension/trace/propagation/TraceMultiPropagator.java

Co-authored-by: John Watson <jkwatson@gmail.com>

* Update api/context/src/test/java/io/opentelemetry/context/propagation/MultiTextMapPropagatorTest.java

Co-authored-by: Anuraag Agrawal <anuraaga@gmail.com>

* Update extensions/trace-propagators/src/main/java/io/opentelemetry/extension/trace/propagation/TraceMultiPropagator.java

Co-authored-by: Anuraag Agrawal <anuraaga@gmail.com>

* Update api/context/src/test/java/io/opentelemetry/context/propagation/MultiTextMapPropagatorTest.java

* suppress warnings

* get spotless

Co-authored-by: John Watson <jkwatson@gmail.com>
Co-authored-by: Anuraag Agrawal <anuraaga@gmail.com>

api/context/src/main/java/io/opentelemetry/context/propagation/MultiTextMapPropagator.java

@@ -7,6 +7,7 @@ package io.opentelemetry.context.propagation;
 
 import io.opentelemetry.context.Context;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.LinkedHashSet;
@@ -18,6 +19,10 @@ final class MultiTextMapPropagator implements TextMapPropagator {
   private final TextMapPropagator[] textPropagators;
   private final Collection<String> allFields;
 
+  MultiTextMapPropagator(TextMapPropagator... textPropagators) {
+    this(Arrays.asList(textPropagators));
+  }
+
   MultiTextMapPropagator(List<TextMapPropagator> textPropagators) {
     this.textPropagators = new TextMapPropagator[textPropagators.size()];
     textPropagators.toArray(this.textPropagators);

api/context/src/test/java/io/opentelemetry/context/propagation/MultiTextMapPropagatorTest.java

@@ -0,0 +1,136 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.context.propagation;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import io.opentelemetry.context.Context;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import javax.annotation.Nullable;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+@ExtendWith(MockitoExtension.class)
+@SuppressWarnings("deprecation") // we're testing deprecated stuff in here.
+class MultiTextMapPropagatorTest {
+
+  @Mock private TextMapPropagator propagator1;
+  @Mock private TextMapPropagator propagator2;
+  @Mock private TextMapPropagator propagator3;
+
+  private static final TextMapPropagator.Getter<Map<String, String>> getter =
+      new TextMapPropagator.Getter<Map<String, String>>() {
+        @Override
+        public Iterable<String> keys(Map<String, String> carrier) {
+          return carrier.keySet();
+        }
+
+        @Nullable
+        @Override
+        public String get(Map<String, String> carrier, String key) {
+          return carrier.get(key);
+        }
+      };
+
+  @Test
+  void addPropagator_null() {
+    assertThrows(
+        NullPointerException.class,
+        () -> new MultiTextMapPropagator((List<TextMapPropagator>) null));
+  }
+
+  @Test
+  void fields() {
+    when(propagator1.fields()).thenReturn(Arrays.asList("foo", "bar"));
+    when(propagator2.fields()).thenReturn(Arrays.asList("hello", "world"));
+    TextMapPropagator prop = new MultiTextMapPropagator(propagator1, propagator2);
+
+    Collection<String> fields = prop.fields();
+    assertThat(fields).containsExactly("foo", "bar", "hello", "world");
+  }
+
+  @Test
+  void fields_duplicates() {
+    when(propagator1.fields()).thenReturn(Arrays.asList("foo", "bar", "foo"));
+    when(propagator2.fields()).thenReturn(Arrays.asList("hello", "world", "world", "bar"));
+    TextMapPropagator prop = new MultiTextMapPropagator(propagator1, propagator2);
+
+    Collection<String> fields = prop.fields();
+    assertThat(fields).containsExactly("foo", "bar", "hello", "world");
+  }
+
+  @Test
+  void fields_readOnly() {
+    when(propagator1.fields()).thenReturn(Arrays.asList("rubber", "baby"));
+    when(propagator2.fields()).thenReturn(Arrays.asList("buggy", "bumpers"));
+    TextMapPropagator prop = new MultiTextMapPropagator(propagator1, propagator2);
+    Collection<String> fields = prop.fields();
+    assertThrows(UnsupportedOperationException.class, () -> fields.add("hi"));
+  }
+
+  @Test
+  void inject_allDelegated() {
+    Map<String, String> carrier = new HashMap<>();
+    Context context = mock(Context.class);
+    TextMapPropagator.Setter<Map<String, String>> setter = Map::put;
+
+    TextMapPropagator prop = new MultiTextMapPropagator(propagator1, propagator2, propagator3);
+    prop.inject(context, carrier, setter);
+    verify(propagator1).inject(context, carrier, setter);
+    verify(propagator2).inject(context, carrier, setter);
+    verify(propagator3).inject(context, carrier, setter);
+  }
+
+  @Test
+  void extract_noPropagators() {
+    Map<String, String> carrier = new HashMap<>();
+    Context context = mock(Context.class);
+
+    TextMapPropagator prop = new MultiTextMapPropagator();
+    Context resContext = prop.extract(context, carrier, getter);
+    assertThat(context).isSameAs(resContext);
+  }
+
+  @Test
+  void extract_found_all() {
+    Map<String, String> carrier = new HashMap<>();
+    TextMapPropagator prop = new MultiTextMapPropagator(propagator1, propagator2, propagator3);
+    Context context1 = mock(Context.class);
+    Context context2 = mock(Context.class);
+    Context context3 = mock(Context.class);
+    Context expectedContext = mock(Context.class);
+
+    when(propagator1.extract(context1, carrier, getter)).thenReturn(context2);
+    when(propagator2.extract(context2, carrier, getter)).thenReturn(context3);
+    when(propagator3.extract(context3, carrier, getter)).thenReturn(expectedContext);
+
+    assertThat(prop.extract(context1, carrier, getter)).isEqualTo(expectedContext);
+  }
+
+  @Test
+  void extract_notFound() {
+
+    Map<String, String> carrier = new HashMap<>();
+    Context context = mock(Context.class);
+    when(propagator1.extract(context, carrier, getter)).thenReturn(context);
+    when(propagator2.extract(context, carrier, getter)).thenReturn(context);
+
+    TextMapPropagator prop = new MultiTextMapPropagator(propagator1, propagator2);
+    Context result = prop.extract(context, carrier, getter);
+
+    assertThat(result).isSameAs(context);
+  }
+}

extensions/trace-propagators/src/main/java/io/opentelemetry/extension/trace/propagation/TraceMultiPropagator.java

@@ -48,8 +48,14 @@ import javax.annotation.concurrent.Immutable;
  * Context context = OpenTelemetry.getPropagators().getTextMapPropagator()
  *   .extract(context, carrier, carrierGetter);
  * }</pre>
+ *
+ * <p>This class is @deprecated and will be removed in 0.14.0. Users should migrate to the
+ * MultiTextMapPropagator in the api.
+ *
+ * @deprecated Use {@link TextMapPropagator#composite}
  */
 @Immutable
+@Deprecated
 public final class TraceMultiPropagator implements TextMapPropagator {
 
   /** Returns a {@link TraceMultiPropagator} for the given {@code propagators}. */

extensions/trace-propagators/src/test/java/io/opentelemetry/extension/trace/propagation/TraceMultiPropagatorTest.java

@@ -30,6 +30,7 @@ import org.mockito.Mockito;
 import org.mockito.junit.jupiter.MockitoExtension;
 
 @ExtendWith(MockitoExtension.class)
+@SuppressWarnings("deprecation") // the class under test will go away soon
 class TraceMultiPropagatorTest {
   private static final TextMapPropagator PROPAGATOR1 = B3Propagator.getInstance();
   private static final TextMapPropagator PROPAGATOR2 =