core,auth: Stabilize auth flow using CallCredentials

As discussed in #1914, we need CallCredentials and MoreCallCredentials
to be stable, but there's less of a strong need for the contents of
CallCredentials to be stable. We're willing to commit to the name,
without needing to commit to the plumbing.

2 files changed, 8 insertions, 2 deletions

diff --git a/auth/src/main/java/io/grpc/auth/GoogleAuthLibraryCallCredentials.java b/auth/src/main/java/io/grpc/auth/GoogleAuthLibraryCallCredentials.java
index 335b8abb0..9cb3ba846 100644
--- a/auth/src/main/java/io/grpc/auth/GoogleAuthLibraryCallCredentials.java
+++ b/auth/src/main/java/io/grpc/auth/GoogleAuthLibraryCallCredentials.java
@@ -69,6 +69,9 @@ final class GoogleAuthLibraryCallCredentials implements CallCredentials {
   }
 
   @Override
+  public void thisUsesUnstableApi() {}
+
+  @Override
   public void applyRequestMetadata(MethodDescriptor<?, ?> method, Attributes attrs,
       Executor appExecutor, final MetadataApplier applier) {
     String authority = checkNotNull(attrs.get(ATTR_AUTHORITY), "authority");
diff --git a/auth/src/main/java/io/grpc/auth/MoreCallCredentials.java b/auth/src/main/java/io/grpc/auth/MoreCallCredentials.java
index 1c67f172e..42e540ba3 100644
--- a/auth/src/main/java/io/grpc/auth/MoreCallCredentials.java
+++ b/auth/src/main/java/io/grpc/auth/MoreCallCredentials.java
@@ -18,15 +18,18 @@ package io.grpc.auth;
 
 import com.google.auth.Credentials;
 import io.grpc.CallCredentials;
-import io.grpc.ExperimentalApi;
 
 /**
  * A utility class that converts other types of credentials to {@link CallCredentials}.
  */
-@ExperimentalApi("https//github.com/grpc/grpc-java/issues/1914")
 public final class MoreCallCredentials {
   /**
    * Converts a Google Auth Library {@link Credentials} to {@link CallCredentials}.
+   *
+   * <p>Although this is a stable API, note that the returned instance's API is not stable. You are
+   * free to use the class name {@code CallCredentials} and pass the instance to other code, but the
+   * instance can't be called directly from code expecting stable behavior. See {@link
+   * CallCredentials}.
    */
   public static CallCredentials from(Credentials creds) {
     return new GoogleAuthLibraryCallCredentials(creds);