Capgemini Senior Software Developer interview questions

2 rounds 1 technical +1hr technical oops ,core java,coding,String coding,Exception handling,Data hiding,Collection framework,Multithreading,Spring ,reverse the string using java code.OOPS concepts (Data Abstraction, Encapsulation, Inheritance, Polymorphism).Multithreading, Concurrency, and Thread Basics Questions.What is defined as an immutable object? How would you create an immutable object in Java.

Took 2 rounds of technical Interview by Video Conferencing, Covering all the aspects present in my resume. Finally they confirmed that I have been selected my phone and email and asked for document submission. The HR called 4 times in 24Hrs for document submission. But then they did not provide any response for more than 20 days and upon calling none of recruiter has clue about the status and started blaming on other HR. Finally after 1.5 months after they confirmed I am selected, they replied back saying position is not available. Very unprofessional behaviour from the recruitment team.