docs: @javax.annotation.Nullable
    private static TagValue getTagValueForDeprecatedRpcTag(
        Map<? extends TagKey, TagValueWithMetadata> tags, TagKey[] newKeys) {
      for (TagKey newKey : newKeys) {
        TagValueWithMetadata valueWithMetadata = tags.get(newKey);
        if (valueWithMetadata != null) {
          return valueWithMetadata.getTagValue();
        }
      }
      return UNKNOWN_TAG_VALUE;
    }