in src/main/java/org/apache/sling/auth/core/impl/SlingAuthenticator.java [1414:1432]
private String getHandlerSelectionPath(HttpServletRequest request) {
final Object loginPathO = request.getAttribute(Authenticator.LOGIN_RESOURCE);
String path;
if (loginPathO instanceof String) {
path = (String) loginPathO;
final String ctxPath = request.getContextPath();
if (ctxPath != null && path.startsWith(ctxPath)) {
path = path.substring(ctxPath.length());
}
if (path == null || path.length() == 0) {
path = "/";
}
} else {
path = getPath(request);
}
return path;
}