ACI Worldwide Senior Java Developer interview questions

hr discussion for initial check, 1 technical discussion. and rejected only project related questions explain architecture.... LDAp.... Singleton class.... exception handling. you are addding elements and deleting at same time in a list.. what will be the size, about project, interviewers were confused and had less knowledge how to manage different user in project, spring security.... whatever u say.. they will not satisfied.... arrogant panel