public RequestContextExporterBuilder attr(String alias, AttributeKey<?> attrKey) {
        requireNonNull(alias, "alias");
        requireNonNull(attrKey, "attrKey");
        defaultExportGroupBuilder.attr(alias, attrKey);
        return this;
    }
Adds the specified {@link AttributeKey} to the export list.
The specified {@code alias} is used for the export key.

@param alias the alias of the attribute to export
@param attrKey the key of the attribute to export
core/src/main/java/com/linecorp/armeria/common/logging/RequestContextExporterBuilder.java