Undeprecates propagation symbols for v6 interop

This undeprecates B3SinglePropagation and enforces at runtime that
`Propagation.Factory#get()` must be implemented. I spot checked all the
implementations on GitHub already do.

Signed-off-by: Adrian Cole <adrian@tetrate.io>

brave/src/main/java/brave/baggage/BaggagePropagation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2023 The OpenZipkin Authors
+ * Copyright 2013-2024 The OpenZipkin Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -18,7 +18,6 @@
 import brave.internal.baggage.BaggageCodec;
 import brave.internal.baggage.BaggageFields;
 import brave.internal.collect.Lists;
-import brave.internal.propagation.StringPropagationAdapter;
 import brave.propagation.ExtraFieldPropagation;
 import brave.propagation.Propagation;
 import brave.propagation.TraceContext;
@@ -198,10 +197,6 @@ static final class Factory extends Propagation.Factory implements Propagation<St
       this.localFieldNames = localFieldNames.toArray(new String[0]);
     }
 
-    @Deprecated @Override public <K1> BaggagePropagation<K1> create(KeyFactory<K1> keyFactory) {
-      return new BaggagePropagation<K1>(StringPropagationAdapter.create(get(), keyFactory));
-    }
-
     @Override public BaggagePropagation<String> get() {
       return new BaggagePropagation<String>(this);
     }

brave/src/main/java/brave/internal/propagation/StringPropagationAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2023 The OpenZipkin Authors
+ * Copyright 2013-2024 The OpenZipkin Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -70,7 +70,10 @@
  * }</pre>
  *
  * @since 5.12
+ * @deprecated As of Brave 5.18, throw an {@link UnsupportedOperationException} in
+ * {@link #create(Propagation, KeyFactory)} instead of implementing it.
  */
+@Deprecated
 public final class StringPropagationAdapter<K> implements Propagation<K> {
   public static <K> Propagation<K> create(Propagation<String> delegate, KeyFactory<K> keyFactory) {
     if (delegate == null) throw new NullPointerException("delegate == null");

brave/src/main/java/brave/propagation/B3SinglePropagation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2019 The OpenZipkin Authors
+ * Copyright 2013-2024 The OpenZipkin Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -18,9 +18,9 @@
 /**
  * Implements the propagation format described in {@link B3SingleFormat}.
  *
- * @deprecated Since 5.9, use {@link B3Propagation#newFactoryBuilder()} to control inject formats.
+ * <p>Use {@link B3Propagation#newFactoryBuilder()} to control inject formats.
  */
-@Deprecated public final class B3SinglePropagation {
+public final class B3SinglePropagation {
   public static final Propagation.Factory FACTORY = B3Propagation.newFactoryBuilder()
     .injectFormat(B3Propagation.Format.SINGLE)
     .injectFormat(Span.Kind.CLIENT, B3Propagation.Format.SINGLE)

brave/src/main/java/brave/propagation/ExtraFieldPropagation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2023 The OpenZipkin Authors
+ * Copyright 2013-2024 The OpenZipkin Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -19,7 +19,6 @@
 import brave.internal.Nullable;
 import brave.propagation.TraceContext.Extractor;
 import brave.propagation.TraceContext.Injector;
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
@@ -190,24 +189,16 @@ public Factory build() {
   /** @deprecated Since 5.11 use {@link Propagation.Factory} */
   public static class Factory extends Propagation.Factory {
     final Propagation.Factory delegate;
-    final String[] extraKeyNames;
+    final List<String> extraKeyNames;
 
     Factory(Propagation.Factory delegate, String[] extraKeyNames) {
       this.delegate = delegate;
-      this.extraKeyNames = extraKeyNames;
+      this.extraKeyNames = unmodifiableList(Arrays.asList(extraKeyNames));
     }
 
     /** {@inheritDoc} */
     @Override public ExtraFieldPropagation<String> get() {
-      return create(KeyFactory.STRING);
-    }
-
-    /** {@inheritDoc} */
-    @Deprecated @Override
-    public <K> ExtraFieldPropagation<K> create(Propagation.KeyFactory<K> keyFactory) {
-      List<K> extraKeys = new ArrayList<K>();
-      for (String extraKeyName : extraKeyNames) extraKeys.add(keyFactory.create(extraKeyName));
-      return new ExtraFieldPropagation<K>(delegate.create(keyFactory), unmodifiableList(extraKeys));
+      return new ExtraFieldPropagation<String>(delegate.get(), extraKeyNames);
     }
 
     @Override public boolean supportsJoin() {

brave/src/main/java/brave/propagation/Propagation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2023 The OpenZipkin Authors
+ * Copyright 2013-2024 The OpenZipkin Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -17,7 +17,6 @@
 import brave.Span.Kind;
 import brave.baggage.BaggagePropagation;
 import brave.internal.Nullable;
-import brave.internal.propagation.StringPropagationAdapter;
 import java.util.List;
 
 /**
@@ -32,9 +31,11 @@
  * request is sent to the server. The server {@linkplain TraceContext.Extractor#extract extracts} a
  * trace context from these headers before processing the request.
  *
- * @param <K> Deprecated except when a {@link String}.
+ * @param <K> Retained for compatibility with pre Brave 6.0, but always String.
  * @since 4.0
  */
+// The generic type parameter K is always <String>. Even if the deprecated methods are removed in
+// Brave 6.0. This is to avoid a compilation break and revlock.
 public interface Propagation<K> {
   /**
    * Defaults B3 formats based on {@link Request} type. When not a {@link Request} (e.g. in-process
@@ -44,17 +45,17 @@ public interface Propagation<K> {
    */
   Propagation<String> B3_STRING = B3Propagation.get();
   /**
-   * @deprecated Since 5.9, use {@link B3Propagation#newFactoryBuilder()} to control inject formats.
+   * Implements the propagation format described in {@link B3SingleFormat}.
    */
-  @Deprecated Propagation<String> B3_SINGLE_STRING = B3SinglePropagation.FACTORY.get();
+  Propagation<String> B3_SINGLE_STRING = B3SinglePropagation.FACTORY.get();
 
   /** @since 4.0 */
   abstract class Factory {
     /**
      * Does the propagation implementation support sharing client and server span IDs. For example,
      * should an RPC server span share the same identifiers extracted from an incoming request?
      *
-     * In usual <a href="https://github.com/openzipkin/b3-propagation">B3 Propagation</a>, the
+     * <p>In usual <a href="https://github.com/openzipkin/b3-propagation">B3 Propagation</a>, the
      * parent span ID is sent across the wire so that the client and server can share the same
      * identifiers. Other propagation formats, like <a href="https://github.com/w3c/trace-context">trace-context</a>
      * only propagate the calling trace and span ID, with an assumption that the receiver always
@@ -78,31 +79,28 @@ public boolean requires128BitTraceId() {
     }
 
     /**
-     * This is deprecated: end users and instrumentation should never call this, and instead use
-     * {@link #get()}.
-     *
-     * <h3>Implementation advice</h3>
-     * This is deprecated, but abstract. This means those implementing custom propagation formats
-     * will have to implement this until it is removed in Brave 6. If you are able to use a tool
-     * such as "maven-shade-plugin", consider using {@link StringPropagationAdapter}.
-     *
-     * @param <K> Deprecated except when a {@link String}.
-     * @see KeyFactory#STRING
-     * @since 4.0
-     * @deprecated Since 5.12, use {@link #get()}
+     * @deprecated end users and instrumentation should never call this, and instead use
+     * {@link #get()}. This will not be removed, to avoid rev-lock upgrading to Brave 6.
      */
-    @Deprecated
-    public abstract <K> Propagation<K> create(KeyFactory<K> keyFactory);
+    @Deprecated public <K> Propagation<K> create(KeyFactory<K> unused) {
+      // In Brave 5.12, this was abstract, but not used: `get()` dispatched
+      // to this. Brave 5.18 implemented this with the below exception to force
+      // `get()` to be overridden. Doing so allows us to make `get()` abstract
+      // in Brave 6.0, but we will have to leave this here regardless, to
+      // prevent revlock upgrading.
+      throw new UnsupportedOperationException("This was replaced with PropagationFactory.get() in Brave 5.12");
+    }
 
     /**
      * Returns a possibly cached propagation instance.
      *
-     * <p>Implementations should override and implement this method directly.
-     *
      * @since 5.12
      */
     public Propagation<String> get() {
-      return create(KeyFactory.STRING);
+      // In Brave 5.12, this dispatched to the deprecated abstract method
+      // `create()`. In Brave 5.18, we throw an exception instead to ensure it
+      // is implemented prior to Brave 6.0 making this abstract.
+      throw new UnsupportedOperationException("As of Brave 5.18, you must implement PropagationFactory.get()");
     }
 
     /**
@@ -126,7 +124,8 @@ public TraceContext decorate(TraceContext context) {
 
   /**
    * @since 4.0
-   * @deprecated since 5.12 non-string keys are no longer supported
+   * @deprecated since 5.12 non-string keys are no longer supported. This will not be removed, to
+   * avoid rev-lock upgrading to Brave 6.
    */
   @Deprecated
   interface KeyFactory<K> {
@@ -147,7 +146,7 @@ interface KeyFactory<K> {
    * Replaces a propagated key with the given value.
    *
    * @param <R> Usually, but not always, an instance of {@link Request}.
-   * @param <K> Deprecated except when a {@link String}.
+   * @param <K> Retained for compatibility with pre Brave 6.0, but always String.
    * @see RemoteSetter
    * @since 4.0
    */
@@ -212,7 +211,7 @@ interface Setter<R, K> {
    * Gets the first value of the given propagation key or returns {@code null}.
    *
    * @param <R> Usually, but not always, an instance of {@link Request}.
-   * @param <K> Deprecated except when a {@link String}.
+   * @param <K> Retained for compatibility with pre Brave 6.0, but always String.
    * @see RemoteGetter
    * @since 4.0
    */

brave/src/test/java/brave/TracerTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2023 The OpenZipkin Authors
+ * Copyright 2013-2024 The OpenZipkin Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -19,8 +19,6 @@
 import brave.baggage.BaggagePropagationConfig.SingleBaggageField;
 import brave.handler.MutableSpan;
 import brave.handler.SpanHandler;
-import brave.internal.Platform;
-import brave.internal.handler.OrphanTracker;
 import brave.propagation.B3Propagation;
 import brave.propagation.CurrentTraceContext;
 import brave.propagation.CurrentTraceContext.Scope;
@@ -42,7 +40,6 @@
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 import org.mockito.Mockito;
-
 import zipkin2.Endpoint;
 import zipkin2.reporter.Reporter;
 
@@ -68,8 +65,8 @@ public class TracerTest {
     .addSpanHandler(spans)
     .trackOrphans()
     .propagationFactory(new Propagation.Factory() {
-      @Deprecated @Override public <K> Propagation<K> create(Propagation.KeyFactory<K> keyFactory) {
-        return propagationFactory.create(keyFactory);
+      @Override public Propagation<String> get() {
+        return propagationFactory.get();
       }
 
       @Override public boolean supportsJoin() {
@@ -229,9 +226,8 @@ public class TracerTest {
   @Test void join_createsChildWhenUnsupportedByPropagation() {
     tracer = Tracing.newBuilder()
       .propagationFactory(new Propagation.Factory() {
-        @Override
-        @Deprecated public <K> Propagation<K> create(Propagation.KeyFactory<K> keyFactory) {
-          return B3Propagation.FACTORY.create(keyFactory);
+        @Override public Propagation<String> get() {
+          return B3Propagation.FACTORY.get();
         }
       })
       .addSpanHandler(spans).build().tracer();

brave/src/test/java/brave/TracingTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2023 The OpenZipkin Authors
+ * Copyright 2013-2024 The OpenZipkin Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -243,8 +243,8 @@ class TracingTest {
     AtomicBoolean sampledLocal = new AtomicBoolean();
     try (Tracing tracing = Tracing.newBuilder()
       .propagationFactory(new Propagation.Factory() {
-        @Deprecated public <K> Propagation<K> create(Propagation.KeyFactory<K> keyFactory) {
-          return B3SinglePropagation.FACTORY.create(keyFactory);
+        @Override public Propagation<String> get() {
+          return B3SinglePropagation.FACTORY.get();
         }
 
         @Override public TraceContext decorate(TraceContext context) {

brave/src/test/java/brave/features/propagation/CustomTraceIdPropagation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2020 The OpenZipkin Authors
+ * Copyright 2013-2024 The OpenZipkin Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -41,7 +41,7 @@ public final class CustomTraceIdPropagation extends Propagation.Factory
   public static Propagation.Factory create(Propagation.Factory delegate, String customTraceIdName) {
     if (delegate == null) throw new NullPointerException("delegate == null");
     if (customTraceIdName == null) throw new NullPointerException("customTraceIdName == null");
-    if (!delegate.create(KeyFactory.STRING).keys().contains("b3")) {
+    if (!delegate.get().keys().contains("b3")) {
       throw new IllegalArgumentException("delegate must implement B3 propagation");
     }
     return new CustomTraceIdPropagation(delegate, customTraceIdName);

brave/src/test/java/brave/features/propagation/NonStringPropagationKeysTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2023 The OpenZipkin Authors
+ * Copyright 2013-2024 The OpenZipkin Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -24,14 +24,15 @@
 /** This shows propagation keys don't need to be Strings. For example, we can propagate over gRPC */
 class NonStringPropagationKeysTest {
   TraceContext context = TraceContext.newBuilder().traceId(1).spanId(2).sampled(true).build();
+
+  // Note: This class will be removed in Brave 6.0, but B3Propagation implements create meanwhile.
   Propagation<Metadata.Key<String>> grpcPropagation = B3Propagation.FACTORY.create(
     name -> Metadata.Key.of(name, Metadata.ASCII_STRING_MARSHALLER)
   );
   TraceContext.Extractor<Metadata> extractor = grpcPropagation.extractor(Metadata::get);
   TraceContext.Injector<Metadata> injector = grpcPropagation.injector(Metadata::put);
 
   @Test void injectExtractTraceContext() {
-
     Metadata metadata = new Metadata();
     injector.inject(context, metadata);
 

brave/src/test/java/brave/internal/extra/ExtraFactoryTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2023 The OpenZipkin Authors
+ * Copyright 2013-2024 The OpenZipkin Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -30,8 +30,8 @@ class ExtraFactoryTest {
       .build();
 
   Propagation.Factory propagationFactory = new Propagation.Factory() {
-    @Deprecated @Override public <K> Propagation<K> create(Propagation.KeyFactory<K> keyFactory) {
-      return B3Propagation.FACTORY.create(keyFactory);
+    @Override public Propagation<String> get() {
+      return B3Propagation.FACTORY.get();
     }
 
     @Override public TraceContext decorate(TraceContext context) {

instrumentation/kafka-clients/src/test/java/brave/kafka/clients/ITKafkaTracing.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2023 The OpenZipkin Authors
+ * Copyright 2013-2024 The OpenZipkin Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -16,7 +16,6 @@
 import brave.Span.Kind;
 import brave.handler.MutableSpan;
 import brave.internal.codec.HexCodec;
-import brave.internal.propagation.StringPropagationAdapter;
 import brave.messaging.MessagingRuleSampler;
 import brave.messaging.MessagingTracing;
 import brave.propagation.Propagation;
@@ -213,10 +212,6 @@ static class TraceIdOnlyPropagation extends Propagation.Factory implements Propa
     @Override public Propagation<String> get() {
       return this;
     }
-
-    @Override public <K1> Propagation<K1> create(KeyFactory<K1> keyFactory) {
-      return StringPropagationAdapter.create(this, keyFactory);
-    }
   }
 
   @Test void continues_a_trace_when_only_trace_id_propagated() {