private boolean isEndpointOverridden(Request<?> request) {
        return Boolean.TRUE.equals(request.getHandlerContext(HandlerContextKey.ENDPOINT_OVERRIDDEN));
    }
{@link RequestHandler2} that modifies the endpoint to handle virtual addressing (account id hoisting),
Dual-Stack, and FIPS.
aws-java-sdk-s3control/src/main/java/com/amazonaws/services/s3control/internal/handlers/EndpointHandler.java