private String countItems; //сколько элементов отдать
private String fromPosition; //с какого элемента отдавать
private String nameMask; // имя
private String phoneMask; // телефон

List result = myRepository.findByFirstNameLikeOrPhoneLike(nameMask, phoneMask,new PageRequest(fromPosition,countItems));

List result = myRepository.findByPhoneLike(phoneMask,new PageRequest(fromPosition,countItems));

List result = myRepository.findByFirstNameLikeOrPhoneLike(null,phoneMask,new PageRequest(fromPosition,countItems));

org.springframework.dao.InvalidDataAccessApiUsageException: [Assertion failed] - this argument is required; it must not be null;