Hardcoded Basic-Auth authenticator for Play2/Java

SingleUserBasicAuthAuthenticator.java

import play.mvc.Http;
import play.mvc.Result;
import play.mvc.Security;

import java.nio.charset.Charset;
import java.util.Base64;

import static java.util.Optional.ofNullable;

/**
 * A very simple basic auth username/password authenticator for use with Play2/Java.
 * 
 * Extracts the username/password from environment variables and defaults to username/password
 * 
 * Environment variables used are "BASIC_AUTH_USERNAME" and "BASIC_AUTH_PASSWORD"
 *
 * Apply to a Play2 controller method with:
 *
 *      @Security.Authenticated(SingleUserBasicAuthAuthenticator.class)
 *
 *  @see play.mvc.Security.Authenticated
 */
public class SingleUserBasicAuthAuthenticator extends Security.Authenticator {
    private static final Charset UTF8 = Charset.forName("UTF-8");
    private static final Base64.Decoder DECODER = Base64.getDecoder();
    private static final String USERNAME = ofNullable(System.getenv("BASIC_AUTH_USERNAME")).orElse("username");
    private static final String PASSWORD = ofNullable(System.getenv("BASIC_AUTH_PASSWORD")).orElse("password");

    public String getUsername(Http.Context ctx) {
        String authorization = ctx.request().getHeader(Http.HeaderNames.AUTHORIZATION);
        if (authorization != null) {
            String[] basicParts = authorization.split(" ", 2);
            if (basicParts.length == 2) {
                String decoded = new String(DECODER.decode(basicParts[1]), UTF8);
                String[] parts = decoded.split(":", 2);
                if (parts.length == 2
                        && USERNAME.equals(parts[0])
                        && PASSWORD.equals(parts[1])) {
                    return USERNAME;
                }
            }
        }
        return null;
    }

    public Result onUnauthorized(Http.Context ctx) {
        ctx.response().setHeader(Http.HeaderNames.WWW_AUTHENTICATE, "Basic realm=\"Please enter details provided\"");
        return unauthorized(views.html.defaultpages.unauthorized.render());
    }
}