Hide default context propagators implementation behind interface.

api/src/main/java/io/opentelemetry/api/DefaultOpenTelemetry.java

@@ -10,7 +10,6 @@
 import io.opentelemetry.api.metrics.MeterProvider;
 import io.opentelemetry.api.trace.TracerProvider;
 import io.opentelemetry.context.propagation.ContextPropagators;
-import io.opentelemetry.context.propagation.DefaultContextPropagators;
 import io.opentelemetry.spi.OpenTelemetryFactory;
 import io.opentelemetry.spi.metrics.MeterProviderFactory;
 import io.opentelemetry.spi.trace.TracerProviderFactory;
@@ -118,7 +117,7 @@ public Builder toBuilder() {
   }
 
   protected static class Builder implements OpenTelemetryBuilder<Builder> {
-    protected ContextPropagators propagators = DefaultContextPropagators.builder().build();
+    protected ContextPropagators propagators = ContextPropagators.builder().build();
 
     protected TracerProvider tracerProvider;
     protected MeterProvider meterProvider;

api/src/test/java/io/opentelemetry/api/OpenTelemetryTest.java

@@ -27,7 +27,6 @@
 import io.opentelemetry.api.trace.Tracer;
 import io.opentelemetry.api.trace.TracerProvider;
 import io.opentelemetry.context.propagation.ContextPropagators;
-import io.opentelemetry.context.propagation.DefaultContextPropagators;
 import io.opentelemetry.spi.metrics.MeterProviderFactory;
 import io.opentelemetry.spi.trace.TracerProviderFactory;
 import java.io.File;
@@ -64,7 +63,6 @@ void testDefault() {
         .isEqualTo("DefaultMeterProvider");
     assertThat(OpenTelemetry.getGlobalMeterProvider())
         .isSameAs(OpenTelemetry.getGlobalMeterProvider());
-    assertThat(OpenTelemetry.getGlobalPropagators()).isInstanceOf(DefaultContextPropagators.class);
     assertThat(OpenTelemetry.getGlobalPropagators()).isSameAs(OpenTelemetry.getGlobalPropagators());
   }
 
@@ -156,7 +154,7 @@ void testMeterNotFound() {
 
   @Test
   void testPropagatorsSet() {
-    ContextPropagators propagators = DefaultContextPropagators.builder().build();
+    ContextPropagators propagators = ContextPropagators.builder().build();
     OpenTelemetry.setGlobalPropagators(propagators);
     assertThat(OpenTelemetry.getGlobalPropagators()).isEqualTo(propagators);
   }

context/src/main/java/io/opentelemetry/context/propagation/ContextPropagators.java

@@ -70,6 +70,28 @@
 @ThreadSafe
 public interface ContextPropagators {
 
+  /**
+   * Returns a {@link ContextPropagatorsBuilder} used to construct a new {@code ContextPropagators}
+   * object with the specified propagators.
+   *
+   * <p>Invocation order of {@code TextMapPropagator#inject()} and {@code
+   * TextMapPropagator#extract()} for registered trace propagators is undefined.
+   *
+   * <p>This is a example of a {@code ContextPropagators} object being created:
+   *
+   * <pre>{@code
+   * ContextPropagators propagators = DefaultContextPropagators.builder()
+   *     .addTextMapPropagator(new HttpTraceContext())
+   *     .addTextMapPropagator(new HttpBaggage())
+   *     .addTextMapPropagator(new MyCustomContextPropagator())
+   *     .build();
+   * }</pre>
+   */
+  @SuppressWarnings("deprecation")
+  static ContextPropagatorsBuilder builder() {
+    return DefaultContextPropagators.builder();
+  }
+
   /**
    * Returns a {@link TextMapPropagator} propagator.
    *

context/src/main/java/io/opentelemetry/context/propagation/ContextPropagatorsBuilder.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.context.propagation;
+
+/**
+ * A builder of a default {@link ContextPropagators} which can have multiple {@link
+ * TextMapPropagator} added, and extraction and injection will execute every {@link
+ * TextMapPropagator} in order.
+ */
+public interface ContextPropagatorsBuilder {
+  /**
+   * Adds a {@link TextMapPropagator} propagator.
+   *
+   * <p>One propagator per concern (traces, correlations, etc) should be added if this format is
+   * supported.
+   *
+   * @param textMapPropagator the propagator to be added.
+   * @return this.
+   * @throws NullPointerException if {@code textMapPropagator} is {@code null}.
+   */
+  ContextPropagatorsBuilder addTextMapPropagator(TextMapPropagator textMapPropagator);
+
+  /**
+   * Builds a new {@code ContextPropagators} with the specified propagators.
+   *
+   * @return the newly created {@code ContextPropagators} instance.
+   */
+  ContextPropagators build();
+}

context/src/main/java/io/opentelemetry/context/propagation/DefaultContextPropagators.java

@@ -21,7 +21,10 @@
  * synchronically upon injection and extraction.
  *
  * <p>The propagation fields retrieved from all registered propagators are de-duplicated.
+ *
+ * @deprecated Use {@link ContextPropagators#builder()}
  */
+@Deprecated
 public final class DefaultContextPropagators implements ContextPropagators {
   private final TextMapPropagator textMapPropagator;
 
@@ -35,8 +38,10 @@ public TextMapPropagator getTextMapPropagator() {
    * object.
    *
    * @return a {@link DefaultContextPropagators.Builder}.
+   * @deprecated Use {@link ContextPropagators#builder()}
    */
-  public static Builder builder() {
+  @Deprecated
+  public static ContextPropagatorsBuilder builder() {
     return new Builder();
   }
 
@@ -45,35 +50,15 @@ private DefaultContextPropagators(TextMapPropagator textMapPropagator) {
   }
 
   /**
-   * {@link Builder} is used to construct a new {@code ContextPropagators} object with the specified
-   * propagators.
-   *
-   * <p>Invocation order of {@code TextMapPropagator#inject()} and {@code
-   * TextMapPropagator#extract()} for registered trace propagators is undefined.
-   *
-   * <p>This is a example of a {@code ContextPropagators} object being created:
+   * A builder of {@link DefaultContextPropagators}.
    *
-   * <pre>{@code
-   * ContextPropagators propagators = DefaultContextPropagators.builder()
-   *     .addTextMapPropagator(new HttpTraceContext())
-   *     .addTextMapPropagator(new HttpBaggage())
-   *     .addTextMapPropagator(new MyCustomContextPropagator())
-   *     .build();
-   * }</pre>
+   * @deprecated Use {@link ContextPropagators#builder()}
    */
-  public static final class Builder {
+  @Deprecated
+  public static final class Builder implements ContextPropagatorsBuilder {
     List<TextMapPropagator> textPropagators = new ArrayList<>();
 
-    /**
-     * Adds a {@link TextMapPropagator} propagator.
-     *
-     * <p>One propagator per concern (traces, correlations, etc) should be added if this format is
-     * supported.
-     *
-     * @param textMapPropagator the propagator to be added.
-     * @return this.
-     * @throws NullPointerException if {@code textMapPropagator} is {@code null}.
-     */
+    @Override
     public Builder addTextMapPropagator(TextMapPropagator textMapPropagator) {
       if (textMapPropagator == null) {
         throw new NullPointerException("textMapPropagator");
@@ -83,11 +68,7 @@ public Builder addTextMapPropagator(TextMapPropagator textMapPropagator) {
       return this;
     }
 
-    /**
-     * Builds a new {@code ContextPropagators} with the specified propagators.
-     *
-     * @return the newly created {@code ContextPropagators} instance.
-     */
+    @Override
     public ContextPropagators build() {
       if (textPropagators.isEmpty()) {
         return new DefaultContextPropagators(NoopTextMapPropagator.INSTANCE);

context/src/test/java/io/opentelemetry/context/propagation/DefaultPropagatorsTest.java

@@ -22,16 +22,15 @@ class DefaultPropagatorsTest {
   @Test
   void addTextMapPropagatorNull() {
     assertThrows(
-        NullPointerException.class,
-        () -> DefaultContextPropagators.builder().addTextMapPropagator(null));
+        NullPointerException.class, () -> ContextPropagators.builder().addTextMapPropagator(null));
   }
 
   @Test
   void testInject() {
     CustomTextMapPropagator propagator1 = new CustomTextMapPropagator("prop1");
     CustomTextMapPropagator propagator2 = new CustomTextMapPropagator("prop2");
     ContextPropagators propagators =
-        DefaultContextPropagators.builder()
+        ContextPropagators.builder()
             .addTextMapPropagator(propagator1)
             .addTextMapPropagator(propagator2)
             .build();
@@ -52,7 +51,7 @@ void testExtract() {
     CustomTextMapPropagator propagator2 = new CustomTextMapPropagator("prop2");
     CustomTextMapPropagator propagator3 = new CustomTextMapPropagator("prop3");
     ContextPropagators propagators =
-        DefaultContextPropagators.builder()
+        ContextPropagators.builder()
             .addTextMapPropagator(propagator1)
             .addTextMapPropagator(propagator2)
             .build();
@@ -76,7 +75,7 @@ public void testDuplicatedFields() {
     CustomTextMapPropagator propagator3 = new CustomTextMapPropagator("prop1");
     CustomTextMapPropagator propagator4 = new CustomTextMapPropagator("prop2");
     ContextPropagators propagators =
-        DefaultContextPropagators.builder()
+        ContextPropagators.builder()
             .addTextMapPropagator(propagator1)
             .addTextMapPropagator(propagator2)
             .addTextMapPropagator(propagator3)
@@ -89,7 +88,7 @@ public void testDuplicatedFields() {
 
   @Test
   void noopPropagator() {
-    ContextPropagators propagators = DefaultContextPropagators.builder().build();
+    ContextPropagators propagators = ContextPropagators.builder().build();
 
     Context context = Context.current();
     Map<String, String> map = new HashMap<>();

integration-tests/tracecontext/src/main/java/io/opentelemetry/Application.java

@@ -10,7 +10,7 @@
 import io.opentelemetry.api.trace.Span;
 import io.opentelemetry.api.trace.propagation.HttpTraceContext;
 import io.opentelemetry.context.Context;
-import io.opentelemetry.context.propagation.DefaultContextPropagators;
+import io.opentelemetry.context.propagation.ContextPropagators;
 import io.opentelemetry.context.propagation.TextMapPropagator.Getter;
 import io.opentelemetry.context.propagation.TextMapPropagator.Setter;
 import java.util.ArrayList;
@@ -36,7 +36,7 @@ public class Application {
     openTelemetry =
         OpenTelemetry.get().toBuilder()
             .setPropagators(
-                DefaultContextPropagators.builder()
+                ContextPropagators.builder()
                     .addTextMapPropagator(HttpTraceContext.getInstance())
                     .build())
             .build();

sdk/testing/src/main/java/io/opentelemetry/sdk/testing/junit4/OpenTelemetryRule.java

@@ -7,7 +7,7 @@
 
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.api.trace.propagation.HttpTraceContext;
-import io.opentelemetry.context.propagation.DefaultContextPropagators;
+import io.opentelemetry.context.propagation.ContextPropagators;
 import io.opentelemetry.sdk.OpenTelemetrySdk;
 import io.opentelemetry.sdk.testing.exporter.InMemorySpanExporter;
 import io.opentelemetry.sdk.trace.TracerSdkManagement;
@@ -56,7 +56,7 @@ public static OpenTelemetryRule create() {
     OpenTelemetrySdk openTelemetry =
         OpenTelemetrySdk.builder()
             .setPropagators(
-                DefaultContextPropagators.builder()
+                ContextPropagators.builder()
                     .addTextMapPropagator(HttpTraceContext.getInstance())
                     .build())
             .setTracerProvider(tracerProvider)

sdk/testing/src/main/java/io/opentelemetry/sdk/testing/junit5/OpenTelemetryExtension.java

@@ -9,7 +9,7 @@
 
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.api.trace.propagation.HttpTraceContext;
-import io.opentelemetry.context.propagation.DefaultContextPropagators;
+import io.opentelemetry.context.propagation.ContextPropagators;
 import io.opentelemetry.sdk.OpenTelemetrySdk;
 import io.opentelemetry.sdk.testing.assertj.TracesAssert;
 import io.opentelemetry.sdk.testing.exporter.InMemorySpanExporter;
@@ -62,7 +62,7 @@ public static OpenTelemetryExtension create() {
     OpenTelemetrySdk openTelemetry =
         OpenTelemetrySdk.builder()
             .setPropagators(
-                DefaultContextPropagators.builder()
+                ContextPropagators.builder()
                     .addTextMapPropagator(HttpTraceContext.getInstance())
                     .build())
             .setTracerProvider(tracerProvider)