V4Context is not Immutable

Author: gosar

core/http-auth-aws/src/main/java/software/amazon/awssdk/http/auth/aws/internal/signer/V4Context.java

@@ -15,15 +15,17 @@
 
 package software.amazon.awssdk.http.auth.aws.internal.signer;
 
-import software.amazon.awssdk.annotations.Immutable;
 import software.amazon.awssdk.annotations.SdkInternalApi;
 import software.amazon.awssdk.http.SdkHttpRequest;
 
 /**
  * A container for data produced during and as a result of the SigV4 request signing process.
  */
 @SdkInternalApi
-@Immutable
+// TODO(sra-identity-auth): This is currently not @Immutable because signedRequest is a Builder. Is Builder needed? If it could
+//  hold reference to SdkHttpRequest instead, this class would be @Immutable.
+// TODO(sra-identity-auth): Consider if we can rename this to convey something more. maybe,
+//  V4RequestSigningResult/V4RequestSigningResultData? Note there is V4aContext similarly.
 public final class V4Context {
     private final String contentHash;
     private final byte[] signingKey;